51 GMC 5 window+S10+5.3/4l60E

[bsccp]

OK, new to the forum. I've been lurking for several months and have learned a tremendous amount from everyone else's experience and builds. So here is my project.

I thought that it wouldn't be too hard to find a 47-54 AD here in West TX. Well guess what? It took the better part of 6 months and several hundreds of miles of driving around and following up on leads. There seemed to be three basic theories on why people wouldn't sell their trucks: 1) belonged to my dad/granddad, etc, very hard to argue with that one, 2) I'm planning on restoring it, or 3) asking way too much money!

After all this time and gasoline it turns out that my neighboor across from my shop (also a fabricator, convienent) had a buddy that had not one, but two for sale. One was a long bed Chevy regular cab and the other was a 51 GMC 5 window! I had hoped for just a regular cab Chevy but ,wow, something a little different. This is some serious farming country around here and I had not expected to find a 5 window GMC. Also, since I was planning on using an S-10 frame I didn't really need drivetrain, etc. Well be careful what you wish for! At that point in time I didn't think $750 for a complete truck was too bad.

Not only did I find my project, "down in the dirt," like I asked for but it had to be chainsawed out of the overgrowth and loaded onto the flatbed with a tractor with a bucket. It took 5 car guys and a fork lift about 30' to off load it into my shop! Never underestimate the advantage of wheels

The S10 was an 83 regular cab, long bed. Perfect, I thought. The owner asked if I wanted the bed and I said I don't need it. For $300 I thought it was a little high but I figured I would salvage what I could and sell the rest for scap. Once again, be careful what you wish for!

Turns out that this had been an abandoned vehicle locally and it was very obvious that it was not a local truck. It looked like it had been back in the rust belt for many years and was literally falling apart. After blowing the front end apart and salvaging what I could electrically, I realized the floor of the cab was rusted through!

The same kind gentleman with the forklift was still helping somebody move out of his shop so we put the forks through the door window opening and lifted it off the frame (cab mounts were totally rusted) and put it on a flatbed and off to the scap yard. Between the engine (2.6 V6) and four speed and cab I netted $120

So, $180 for the frame was OK. Rear end is junk, front suspension will be replaced with late model Blazer and the gas tank will be replaced with a plasitc S10 unit and wiring will be reviewed.

In my part of the world I can get a complete "takeout" 5.3 with wiring, computer, etc for around $700 and I have a very good tranny shop that will let me use a 4L60E core for mock up. He charges $800 for an excellent rebuild with converter, aftermarket shell and Vette servo.

So that's the start. More to come.

[SouthernRodder]

Hey man. Looks like you got a good start. I love the patina on that 5 window. I'm in the process of the same swap onto a 98 frame. I am using the Vortec 4.3, just for something a little different, plus it's FREE. Good luck. I look forward to seeing more progress.

[bsccp]

Here are two of the best shots of the S10. On the way to the scrap yard and just the frame! The amount of mud and rust was incredible. I used a power washer on the frame just to make sure there wasn't any suprises.

Finally with the GMC in the shop I started to evaluate/disassemble. Bed turned out to be not usable. Fenders were not too bad but the front and sides had been welded to a "bed liner" made from 1/8" steel. It took 6 cut-off wheels to free it up. Couldn't use a torch since there was still wood in the bed

Cab had the usual rust: both floorboards and a little of the toeboards, both interior cowl pieces will need to be replaced but only the passenger side outer cowl (about 3-4" on the bottom) and a hole about 4' behind the gas tank on the back of the cab. So all in all, not too bad.

The best tool I have at this point in time is my trusty 4 1/2" grinder and several 10 packs of cut-off wheels from Harbor Freight. Every single nut and bolt is rusted/seized. I've tried several different rust penatrators and a mechanic friend gave me a can of GT-85 which seems to work the best but otherwise I either snap the bolt or cut it off. What a slow process!

[duwem]

Cool project! Saved one from rotting to the ground. I would keep the paint as is for the time being, would be a real sleeper with a 5.3L in it and that weathered paint.

[bsccp]

Bed disassembly: Never having taken one apart and working by myself it seemed logical to start on one side and work my way across.

Since every single nut and bolt was rusted I started with the passenger side fender and running board. The fender had some front rust but had been hit a couple of times. Nothing serious but ratty.

Then went to the bedside. That was a totally different story. Front panel and support were rusted badly on the bottom so was the bedside. Cut off the support rail bolts and lifted it off. That gave me access to the bed lumber and strips.

I tried several different approaches to removing the bolts and went back to the old standby. Grinder with cuf off wheels. Cut the heads off (there seemed like a thousand by the time I got done) and worked my way across to the passenger side. Original lumber, still painted black on the bottom side.
I may reassemble the bed this way. Way easier to handle the pieces and should still be able to get to the new lumber and strips by doing a row at a time.

Drivers side came off easier but the two rear bolts on the rear fenders are kinda tucked away so that earned some foul language.

Cab disassembly: Doors first. One still had glass so I tried to save it in case I wanted a local shop to use it as a template. Never mind, way too difficult to remove. Lots of penetrating spray to save the regulators and not destroy the door, hinges or sheetmetal. Did well till I got to the vent windows. Definitely an art form. One has to pay attention to all the trim. I bagged and tagged all the trim pieces and screws. Will replace all the trim screws with new. I successfully removed all but one door jam bolt. Between the impact driver, penetrating oil, and bolt extractor the rest came out ok. The striker screws were a little tougher. Had to drill out one screw on each side top so that I could remove the backing bar and remove the striker!

At this point the headliner was sorta still in place but after seeing several spiders I decided to finish removing the support brace and front and rear trims pieces. Have I mentioned how much dirt was in the cab? If not I will probably mention it several more times. As I said earlier, I was looking for a truck that had been "down in the dirt" and brother did I get my wish. I had already power washed the entire truck before putting it in the shop but that only removed the external dirt! Not the 20 poiunds inside the cab.

[bsccp]

A couple of more comments on cab disassembly:
Gas tank came out ok and looked pretty good except for the additional 5 lbs of dirt underneath it. Then noticed that the back of the cab had a rust hole and after closer inspection realized it went almost all the way across. Another patch panel.

Seat frame was a PITA to remove. I have a spot weld cutter and a good quality 5/16" drill bit but due to the upper lip on the frame it was very difficult to get the right angle to cut the spot welds. They were also very difficult to see even with wire brushing the rust off!

Finally used the trusty grinder/cut off combo and sliced the frame at the floor and then went back and removed the remaining strip. I've used the spot weld cutter before and have had good success with it but after putting some additional holes in the floor I decided to cut the remaining strip off between welds and cut the welds parallel with the floor pan!

It seems to me that the seat frame was also a stiffener for the floor pan. I'm thinking that some additional 1' x 1" square tube between the rear supports and around the front supports and tie them together will restore the floor stiffness. I maybe using late model Blazer seats and console so I will need something to tie them to.

Removing the pieces to the dash was slow due to the dirt again and everything being rusted together. I knew the steering column support was toast but I didn't know how bad.

The support brace was still bolted to the firewall but was broken at the dash. The dash has multiple fatigue fractures and the under dash bolt/mounting bracket were broken free! In other words many miles of rough road and constant pounding. The steering box was tight and unbroken but everything else in what was left of the front end was worn out.

Went to stovebolt.com to figure out how to remove the steering wheel and short of fabbing up a puller I tried to pull it from the steering box! The column will not pull out of the worm gear but by backing out of the worm it will free up the outer part of the column. Using redneck engineering I removed the horn button and backed off the nut until it was almost off and using a BMFBPH I gave it a few whacks and separted the steering wheel from the column! Then removed the steering box from the frame and drag link (which was so worn out it fell off the pitman arm).

By comparison the front end was easy!

[LEEVON]

Nice start. You're more patient than me with the steering column. I looked, scratched my head, looked again, removed a bunch of bolts without much thought, scratched my head then got the cut-off wheel.

[bsccp]

Frame pictures: Gonna skip a few steps. I have never seen a picture type comparison of the S10 frame to the original AD frame. Well here they are.

As you can see they are fairly close, both in length and width. The AD frame is pretty straight without much kickup and tapers front to back. The S10 has the kickout for the cab but much more pronounced dip in the frame rails.

I did put some silver paint on the S10 frame to give me reference points when I start to position the cab.

FYI: As far as I know this is not an unnatural act in TX

[1952ssr]

It's funny you post the frame on frame comparison. If I did a s-swap again I had the thought of taking the original frame cut the front and back off then graft it to the s10 frame retaining all the factory mounts for the cab.

[bsccp]

Updates: Life just gets in the way of having fun!

Like a lot of people it took me forever to start making the first cuts. Since my donor chassis is an early S10 ('83) the front frame horns are a little different than the newer S10's.
I finally decided to cut 8" off. Since my truck is a GMC I wanted to make as few cuts as possible on the front end sheet metal to retain the GMC look.

Then came the challenge of trimming the inner fenders to clear the suspension. After much trial and error I got close and then started working on centering the wheel wells.

Taking suggestions from others I had found the axle center on the original front end and then drilled a small hole and used a small sheet metal screw to hang the pendulum to find center. Then used a framing square to make sure my eyes weren't off

Discovered a couple of things: You can't go back much further than 8" due to forward bolt on the steering box. After trying to line up the 1x2 tubing that I used as the lower brace I found out that I hadn't made my cuts square. In hindsight there are two different reference holes on the bottom of the early frames that would have made it easier.

My S10 didn't have a sway bar so I went to the local yard and bought one off a '98 Blazer. 33 mm with all brackets - $50. Mounted it up to make sure it would clear the 1x2 and then discovered two different ways to measure more accurately. One reference is the forward bolt hole for the sway bracket. Mine was 2 3/8" back from my cuts (kinda since I was off on the passenger side). There is also another frame hole in front of the sway bracket hole that is not threaded but appears to be the same on both frame rails.
I had a thought that one could bolt the lower bracket to the frame rather than welding it on if you thought it might need to be replaced. You could reuse on of the frame clips and OEM bolts to hold it. Since the 1X2 is about the same level as the sway bar I figured that if I hit something that would require the lower brace to be replaced a lot of other things would be damaged too!

Taking liberties with Bartman's design I decided to mount the ! x 2 x 1/8" below the frame rails. Once again the steering box problem. It seemed to give a little more clearance. Using the 1 x 2 again I angle cut the verticles at about 7 1/2". I am using stall mat that is about 3/4" thick as a cushion between the radiator frame and the support bracket. Using grade 5 5/16" x 3 to bolt it together that also allows for shimming just in case.

Then cut a 12 1/2" horizontal piece to top the risers. I used a piece of 2 x 2 x 1/8 as the bottom piece in the radiator frame and mounted it directly on top of the lower two capture nuts. Left about 1" of frame below the capture nuts just for some meat.

Since my truck is a GMC and I wanted to keep the front end sheet metal this arrangement worked out pretty well. The center piece fits nicely and I will use a piece of 2' x 1/8 and use self tapers to anchor the center piece. Changed the angle of sheet metal to match the verticle risers but it wasn't too bad. Had to trim both of the side brackets, that mount between the radiator frame and inner fender, to clear the steering box bolt boss and the passenger side frame but as you can see in the picture it will finish off nicely. Need to trim the outer pieces a little bit to clear the frame but not too much. Most of it is out of sight.

Plan to cap the frames and then move on to the cab mounts. Gonna use 4 x 4 x 1/8 and the cab mounts from the Suburban/Tahoe. Bigger with a flat top but the mounting hole is exactly like the S10!

PS I haven't touched my MIG in 5 years so for those of you that are welder/fabricators; please be nice I also ran out of 90/10 when I started and didn't realize I was out of gas until the first few passes and said WTF? So the tack welds are flux core until I can get my cylinder exchanged.

PPS Some will say why didn't you use 1/4" instead of 1/8"? I miked out the existing frame, supports and the original supports and the max thickness I got was .140" with most of them being between .125 (1/8) and .135. That's my rationalization and if it falls apart and I die then I was wrong

[BlueJeep]

Looks good! 1/8" is plenty thick for the body mounts as long as they're engineered properly. Like you said, that's what the stock ones were. Looks like you need to slide the cab back a bit more by the picture of the front wheels, maybe 1" or so.

[62ChevyII]

Originally Posted by BlueJeep

Looks like you need to slide the cab back a bit more by the picture of the front wheels, maybe 1" or so.

Blue Jeep is right. The front wheel will move back a little when the truck is sitting down on the suspension. They look fine if the wheel is a little forward in the wheel well but they look messed up if the wheel is too far back. Just my opinion.

[bsccp]

Thanks for the input. I thought that the steering box was a pain but trying to figure our the wheel position is equally frustrating!

I agree it doesn't look far enough back. The way GM engineered the opening and the additional front end sheet metal and bumper kinda dictates a little more forward. So much for using the plum bob and square, the human eye is still pretty good.

For those of you curious to know why I didn't use the bottom of the radiator surround, Check out the two pics. Why it was so badly rusted I don't know but it is bad. You can also see the mounting holes for the front center, inner panel.

I'm still probably going to use the bigger suburban/tahoe body mounts. As you can see in the pic they are way bigger, flat topped and have the same mounting hole as the S10.

[Kabwe]

Welcome to the site and thanks for posting pics. I love looking at build threads.

[bsccp]

OK here are the "improved" pics of the front. Taking the suggestion of about 1" did the trick. Now will have to recut the verticle pieces on the radiator support for more of a lay back position and then move on to the cab mounts.

But the front fender level and the cab position (with a 3/4" front cab mount shim) are pretty good As you can see it puts the wheel well center about even with back edge of the spindle. Those are 215 70 x 15" tires by the way. Planning on running much bigger tires toward the end but it was hard enough getting 4 matching rims with the 4 3/4" bolt patterns. 80's Caprice I think.

Will have to retrim the front sheet metal a bit to compensate for the reposition but not a big deal. Most of the big hacking has been done already.

Have the 5.3 already just need the bellhousing and tranny to mock up the engine mounts and position the tranny mount.

[bsccp]

OK, I've discovered I'm not the fasted builder in the west but here is an update on the project:

My S10 donor was very rusty, including the body mounts. I went to the local salvage yards and found that the Suburban/Tahoe?Silverado body mounts were much more abundant and bigger (4" vs 3" OD) but had the same 2" mounting hole! (thanks GM). Decided to use 4x4x1/8 square tube with 4x1/8 flat plate as a cap. Worked great for the rear, spans the rear cab supports, but the front of the cab has a taper toward the firewall. Cut the top at a slant from 4"-3" and left about 1" clearance between the mount and the sheetmetal. Will also reinforce the mounts with pieces welded to the top of the frame for additional support.

I will sandwich mudflap rubber top and bottom with a piece of 4x1/8x4" flat stock for the anti-squeak and increase the mount surface area.

Used 3x3x1/8 for the vertical supports on the bed.Then capped them with 4x1/8 flat stock to give a little more mounting and adjustment area. That is bed #2. The first one was so rusted out along the bottom that I couldn't get a fix on level or even where the original supports went. The current bed was used as a welding trailer! Pretty good shape but someone crunched the drivers side fender. May be fixable, my next door shop buddy has a sheet metal guru with an English wheel and some skills so maybe?

Cutoff approximately 5 1/2" from the rear frame rail to mount the bed. Will turn the rear frame support from the S10 180 degrees and weld it in place for additional support. Will use the stock gas tank (will replace the metal one with a plastic one because I have no idea how bad it is) and exit the side panel.

My setup places the bed about 2 3/8" higher than stock. I plan to fill in the bed side panel with a piece of 18 ga to span the distance to the running board filler. Dropped the rear fenders 2 1/8" to get running board alignment.

The running board supports are still a work in progress. I'm pretty big so I went with 1x2x3/16 channel for the running board supports. The S10 frame has some curve to it so each one is a little different just like the originals! Took a while to get them adjusted so that the running boards were fairly level. If you look at the first pics you can see that the truck was actually resting on the running boards. It took a bit of coaxing with a 2 1/2# ball peen to get them sorta straight.

Due to the bigger mount the front running board support will have to be relocated about 2" rearward. The center one is just in front of the rear mount but the rear support had to relocated due to the kick up of the frame. Thank goodness the running board mounting brackets are available so I'll just cut off the old ones and relocate them so that the running boards can be adjusted and/or removed if they get damaged!

[bsccp]

It's a roller! Finished off the running board mounts and now on to the drive train.

My very nice transmission guy has loaned me a "core" 4l60E with the correct bellhousing and tailshaft for my 5.3. The only thing that slowed me down this weekend was work on Friday! I needed to find a small piece of 3/8 plate for the motor mounts and the only place locally that has a "scrap" yard was not open on Saturday. Oh well, they're open on Tuesday.

Planning on using the S10 transmission cross-member. If I have any hassles I will convert to the 80"s pu style.

[99 to Life]

loving the truck. great patina. I went the same route. only I lowered mine. I am also running 1.5" spacers up front and 2" in the back. I think it gives it a great look. keep it up, you'll get there. btw, that stock s-10 trans xmember most likely won't work. Isn't much to fab it or make a new one.

[bsccp]

More on the 5.3 motor mounts. Had to source a power steering pump for my 5.3 in order to make sure about the clearances between the steering box, motor mounts and front cross member. I used a piece of 3/4" to gap the pan to front cross member and saw that the clearance between the pulley and the steering box was kinda snug. I'm using a piece of 3/4' conduit to get an idea of column layout and it was a bit close also. Running the stock truck pan, plenty of room.

Then used a 2x4 (1 1/2" clearance) between the pan and cross member and things were much better. However, the location of the mounting bosses on the 5.3 are about 3" behind the stock S10 mounts. I've already anticpated this and bought some 5" x 3/8" flat stock to allow for the mounts to be repositioned. I bought the Trans Dapt p/n 4516 for the 2.8 v6 that was in my donor S10. For $80 it was worth my time because it included two new clamshell motor mounts that would have been $20 at Orielly's, so the motor brackets were $50. I'm sure some will say make your own but for me it was easier and faster.

The different websites for the S10 show that the biggest problem with the LS swap is hood clearance, distance to radiator and exhaust manifolds. For the AD I have plenty. The other pictures show the truck exhaust manifolds. Passenger side is fine and the driver side will almost clear the frame but I will look for the 98-99 F-body manifolds to see how it works. Notice that by raising the motor up a bit the manifolds are not a problem with the steering column. Will have to relocate the A/C compressor to a high mount as the stock LS mounting position puts it right on top of the upper a arm. The S10 group position their engines forward and notch the frames for the low mount.

Also notice that the firewall clearance for the engine (and coil packs) is great and that the position of the trans may only require a small radius cut to clear the firewall. I don't have a degree/tilt gauge (Harbor Freight here I come) to dial in the 3 degrees but by the time I have the mounts I will have the trans cross member and will dial it all in.

Secondary thought: Has anyone pushed their engines up about an 1" above the cross member mount position? Just by eyeball I'm guessing that to mate up the motor mount to the block bracket it may require about an 1" spacer to line it up to keep the clearances I have now. A short piece of 1x6x1/4" square tube behind the 3/8 plate?

[OKGMC4]

Also consider the vette manifolds, they fit more like a block hugger header with a center exit. I found them to be a better fit on my 5.3l. I like the way this one is coming together.

[lpguy]

Im gonna be going the same route with the 5.3 and s10 route so this will be really helpful... When you get it in final position can you please take a wider picture to show where front of motor is compared to front of steering box. I wanna see how much room in front of the motor you have

[bsccp]

Received the Trans Dapt from Jeg's today. Way to go Jeg's!

Motor bracket is very nicely done with 5/16" and the clamshells look pretty decent. Loaned my camera to my daughter so I will have to get my wife's camera so that you can see how close the fit is!

It looks like a 7" piece of 3/8" x 5 will be almost perfect as to height! Weld in the front part and drill/bolt the motor mounts in place. Figured that if I want to do any future work it would be easier than to weld everything in place. Time and vibration will tell!

I was concerned about having too much of a lever effect from the engine weight on top of the 3/8" plate but this arrangement is pretty close to the crossmember and actually thicker than the crossmember!

I've located some F-body manifolds locally so I'll go check out how they work with this setup. Vette manifolds are a little harder to come my in my part of the world

[bsccp]

Here are the secondary stage pictures of the motor mounts.

It's actually a 9" piece of 3/8' x 5". On the drivers side I drilled the three mounting holes in the cross member pattern to allow for two of the three bolts to be accessible from the bottom of the plate. The forward hole will be drilled into the cross member and accessed from the front. The early cross members are asymmetrical from drivers side to passenger side but I decided to make both mount plates the same. Seemed logical.

On the passenger side I flipped it over with two holes on top and the single hole on the bottom. All three of these will be accessible from behind the plate.

Using the 10mm bolts from the Trans Dapt kit with 8.8 shouldered nuts. The front of the plates will be about 1/2" back from the cross member. Should allow for significant surface area for a good bead.

It looks like I will need to radius the top trailing edge to make sure there is enough clearance on the rear upper arm. Both mounts are at the bottom of their travel in the slot.

The engine is about 8 degrees of tilt right now. I will radius the firewall to move the trans up and the position the trans cross member. I have a trans cross member out of a '99 S10 that I will try first. It is very similar to the full sized truck but with the mounting holes for the S10. Since I'm using a 4L60E the mounting pad will be the same and help to center the trans.

[changethis]

Make sure you have enough room for your air intake between the front of the moter and radiator. I had to move my moter back to where the coil pack just barely cleared the firewall. I am also using a set of s10 conversion headers on mine and they clear everything real good. Glad to see somebody else is doing a GMC with the ls1.

[bsccp]

thanks showme49 for the heads up on the air intake. I'll have to borrow the wife's suburban and see what the clearances are. I think I have enough room to use the mechanical fan but I need to check that also.

I'm pretty sure the F-body exhaust will work but I need to track down the ones locally.

Two questions: How many degrees of tilt did you use (one site says 4 degrees for the ls series, my mechanic guru says 3 is ok, not a big deal but just curious). My 4L60E fits pretty well with a small radius out of the firewall, but what trans cross member did you use? The S10 will not work without some major cutting. The frame rails open up and taper in my setup position and I'm sure yours do also. Will probably wind up using the 88-98 full sized pu cross member, just have to find one at the local yard.