Gifted a 68 c20- what to do

[Woody2shoez]

Hey guys, first post.

I’ve recently been gifted a 68 c20 from my wife’s grandfather. The truck has a sm465 with an in-line 250. It however does not have the original rear because he didn’t like how low it was and rather than changing the gear ratio put in another vehicles full float rear. To my understanding the Eaton rear doesn’t have a lot of ration options anyway.

The plan is to do a v8 and tranny swap and keep things fairly simple. However I’m having trouble deciding which route to take. I would like an overdrive trans and really am struggling to find which one to go with. My budget is 8k and I’m aware I’ll likely go over that. But if I say 8k and I go 11 I’m alright. I plan to lower the truck and have ac as well.

The motor I’m looking at is a blueprint motors 350 with 375hp and 420t. On top I’d like to do a fitech fuel injection set up.

Now the fun part... the trans. What is the best bang for buck route to go? 700r4 has issues with tv cable on the fitech. Th350 doesn’t have overdrive and I’ve delt with that before. Gear vendors added to the th350 is expensive. 4l60 isn’t all that cheap or easy. T56 isn’t all that cheap. I haven’t heard of anyone doing the nv4500 so I can’t find any info. Anything I’m not thinking about?

Now driving the th350 without the gearvender is what I keep falling back on for expense reasons. The idea would be I’d be able to have a drivable vehicle while I look for a used gv or save for a new one.

Any ideas would be greAtly appreaciated
Thanks
-Woody
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[GASoline71]

With a 3/4 ton and a big ol' FF rear end... you'll need to make sure the transmission you selct will handle the load and the TQ required to move it.

Gary

[Woody2shoez]

Originally Posted by GASoline71

With a 3/4 ton and a big ol' FF rear end... you'll need to make sure the transmission you selct will handle the load and the TQ required to move it.

Gary

So I currently have th350 that I would have rebuilt pretty stout if I decided to go that route. I really like the idea of the 700r4 but am scared of the tv cable adjustment. Is there any manual transmissions that I’m not thinking about that are common swaps and don’t cost a fortune?
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[HO455]

Welcome aboard. Looking forward to some photos of your gift. In the mean time here is a link to let you compare transmissions.

https://www.novak-adapt.com/knowledg...ssions/manual/

Lots of options for you. In my mind the gearvendors vs other factory automatic overdrive trannys comes down to two differences. The factory ones get you a lockup converter which gets a mpg payback over the long run. The gearvendors gets you a more rugged transmission package. Now there are some very strong opinions about newer 6l80e and other such transmissions but the cost of them to me is too much and I would never see a payback for that type of conversion. So towing or cruising/daily driver is the decision. Just my opinion so your results may vary.

[Rufas]

Originally Posted by Woody2shoez

Hey guys, first post.

I’ve recently been gifted a 68 c20 from my wife’s grandfather. The truck has a sm465 with an in-line 250. It however does not have the original rear because he didn’t like how low it was and rather than changing the gear ratio put in another vehicles full float rear. To my understanding the Eaton rear doesn’t have a lot of ration options anyway.

The plan is to do a v8 and tranny swap and keep things fairly simple. However I’m having trouble deciding which route to take. I would like an overdrive trans and really am struggling to find which one to go with. My budget is 8k and I’m aware I’ll likely go over that. But if I say 8k and I go 11 I’m alright. I plan to lower the truck and have ac as well.

The motor I’m looking at is a blueprint motors 350 with 375hp and 420t. On top I’d like to do a fitech fuel injection set up.

Now the fun part... the trans. What is the best bang for buck route to go? 700r4 has issues with tv cable on the fitech. Th350 doesn’t have overdrive and I’ve delt with that before. Gear vendors added to the th350 is expensive. 4l60 isn’t all that cheap or easy. T56 isn’t all that cheap. I haven’t heard of anyone doing the nv4500 so I can’t find any info. Anything I’m not thinking about?

Now driving the th350 without the gearvender is what I keep falling back on for expense reasons. The idea would be I’d be able to have a drivable vehicle while I look for a used gv or save for a new one.

Any ideas would be greAtly appreaciated
Thanks
-Woody
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Where did you hear that about 700R4 and FiTech? Someone has really misinformed you about that. I'm running an 700R4 with FiTech in both my 67 Cutlass with a 468 BBC and my 70 GMC supercharged 350 with FiTech. On the 67 Cutlass the 700R4 has been installed since 2011 without issues. The 468 was dyno'd at 518HP and I have not gone easy on the 700R4. If your worried about the TV cable adjustment just have it adjusted after your get it running. The TV adjustment is not that hard.

1967 Cutlass with 468 BBC with R700 trans


1970 GMC C2500 with R700 Trans



Bowtie Overdrives Patented TV Made Ez system. I'm using that on both the Cutlass and the GMC. BowTie will modify the Holley Carb system for the FiTech.

[WhiteCST]

First off, that’s awesome he just gave it to you. Hard to beat a 5.3/6.0 with a 4l80e combo. Good power and torque stock DIRT cheap. Not to mention can handle pretty high boost reliably so running lower boost would be no problem. You could probably get motor and trans for less than or slightly more than the blueprint motor (especially if you go 5.3) leaving lots of budget for the drop and any interior or bodywork it needs. You mention the 4lxxx series being difficult but paired with the engine and computer it was meant to be with, it doesn’t take much to get it going. I’ve read accounts of highway mileage being between 20 and 25 with 3.73 gear. Just my .02!

[WhiteCST]

Originally Posted by Rufas

Where did you hear that about 700R4 and FiTech? Someone has really misinformed you about that. I'm running an 700R4 with FiTech in both my 67 Cutlass with a 468 BBC and my 70 GMC supercharged 350 with FiTech. On the 67 Cutlass the 700R4 has been installed since 2011 without issues. The 468 was dyno'd at 518HP and I have not gone easy on the 700R4. If your worried about the TV cable adjustment just have it adjusted after your get it running. The TV adjustment is not that hard.

1967 Cutlass with 468 BBC with R700 trans


1970 GMC C2500 with R700 Trans



Bowtie Overdrives Patented TV Made Ez system. I'm using that on both the Cutlass and the GMC. BowTie will modify the Holley Carb system for the FiTech.

Rufas your truck is sick.

[Rufas]

Originally Posted by WhiteCST

Rufas your truck is sick.

Thanks.

My wife uses that term but with a different meaning.

[clay68c10]

The NV4500 is a great transmission. A little scarce in Chevy applications, but they are out there. Ive seen a few for sale on CL up and down the front range. I have one in my 93 and I really like how it drives.
Any pics of the truck?

[Benjamin]

First of all, CONGRATS on the truck, that is awesome.

Don't blow your budget on the motor and transmission because you will probably want to do a few other things on the truck, like convert to disk brakes in the front and replace or upgrade any items that need it (fuel pump, radiator, charging system, etc...).

I am going round and round on some of the same questions you are, and I feel like I am zeroing in on 2 things.

1. I agree with you on the fuel injected small block. LS swaps are cool, and they might get you a little better fuel mileage, but I don't need to do tire-melting burnouts with my truck, and there are lots of hidden costs on an LS swap.

2. Manual transmission all the way. No kick down cables. KISS (Keep It Simple Son). But that is just my preference. If you want an automatic, go for it.

I have an SM465, which I would like to keep, and I am considering adding a Ranger Torque Splitter. That would give me 27% overdrive, or a top gear of 0.73:1, and I could run in overdrive (or "split") in all my other gears, theoretically having the perfect gear for any hill. The only catch with that plan is that they are about $1600-1700, and I will have to get new driveshafts to account for added gearbox length.

The NV4500 looks like a good option for you, do some shopping, but I just saw one on eBay for $1100. NV4500 is rated for a Max Engine Torque of 460 ft*lb & Gross Vehicle Weight of 15,000 lbs, so I would say it's PLENTY stout. Also, look for one from a 92-94 GM application so you get the lower first and reverse, 6.34:1 (granny) 1st gear. Most guys don't use the granny gear on regular old flat ground driving, but on a hill start or trying to navigate a tight parking spot, the granny gear is your best friend, and the lower the better.

[Woody2shoez]

Thank you for all the replies.

I like the idea of a modern engine trans combo however I’m concerned with a few things. It won’t be simple like I plan. To keep it reasonably priced the motor and trans most likely will be tired and I’ll have to put a lot of work into searching. However the daily driving comforts have me coming back to this option time and time again.

The issue I read about with r700 was one gentleman that fried a trans because it wasn’t hooked up to his fitech properly. He couldn’t figure it out and that’s all I could find on the combination. Also you vehicles look amazing.

The truck started its life pulling planes to the runway at Bakersfield airport in California then my wife’s grandfather used it as a farm truck around 80s. It sat for years till he brought it back to life for my wife to drive on occasion in high school. Now it just sits on the farm doing nothing. Being a California desert truck it has very little rust and the body is clean.

I really like the idea of the nv4500 but was worried it might be too clunky having never shifted one. You both have swayed me in that direction and I’m probably going to start planning for that.

Pics will be up soon as I pick the truck up in two weekends.

Thanks again
-Woody
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[Benjamin]

HAHA. I would not call an NV4500 "clunky." The SM465 though, that is a different story, it is definitely a clunky transmission, but I love mine.

One more thing to consider, a 1992 Chevrolet C2500 with a 350 and a 5 speed manual (the NV4500) had an EPA mileage rating of 12 city and 17 highway. The C1500 was a bit better at 13/18 mpg city/highway. I would guess that one difference between the 1500 & the 2500 is rear end gear ratio.

https://www.fueleconomy.gov/feg/Find...on=sbs&id=9247

Sounds like the previous owner was headed this direction with the rear end swap. If you want to do any highway or freeway driving, or if you are interested in fuel mileage, you probably want to be 3.54:1 or higher, which means numerically lower (3.07:1 or 3.08:1)

My point is that the "old" drive trains aren't obsolete. If you build or buy a motor spec'd similarly to the 1992 Vortec (not the 1999 and up Vortec, that would be an LS) then theoretically you could achieve similar fuel mileage. Fuel injection should go a long way towards getting good gas mileage and having good driveability.

Assuming fuel mileage is a function of motor, transmission, rear end gearing, and aerodynamics, you could replicate many of these in the old truck.

[HO455]

One way to decide if you want a NV4500 would be to go test drive a used truck with one. That would give you a basic idea of what to expect.

[WhiteCST]

Modern engines don’t have to be tired to get a good price. A 5.3 Vortec can easily be found in the 60-80k range in my area for under $1000. With a 4l60e you can get a package deal. Usually $1200 ish for a reasonably low mile combo. These engines are good into the 300k range with maintenance.

[Woody2shoez]

Originally Posted by WhiteCST

Modern engines don’t have to be tired to get a good price. A 5.3 Vortec can easily be found in the 60-80k range in my area for under $1000. With a 4l60e you can get a package deal. Usually $1200 ish for a reasonably low mile combo. These engines are good into the 300k range with maintenance.

So I know there is plenty of “how toos” online but what would you say the difficulty level in comparison to just an older style motor would be to do this swap? Even if that swap cost 3to4k it seems like the way to go.
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[Woody2shoez]

Originally Posted by Benjamin

HAHA. I would not call an NV4500 "clunky." The SM465 though, that is a different story, it is definitely a clunky transmission, but I love mine.

One more thing to consider, a 1992 Chevrolet C2500 with a 350 and a 5 speed manual (the NV4500) had an EPA mileage rating of 12 city and 17 highway. The C1500 was a bit better at 13/18 mpg city/highway. I would guess that one difference between the 1500 & the 2500 is rear end gear ratio.

https://www.fueleconomy.gov/feg/Find...on=sbs&id=9247

Sounds like the previous owner was headed this direction with the rear end swap. If you want to do any highway or freeway driving, or if you are interested in fuel mileage, you probably want to be 3.54:1 or higher, which means numerically lower (3.07:1 or 3.08:1)

My point is that the "old" drive trains aren't obsolete. If you build or buy a motor spec'd similarly to the 1992 Vortec (not the 1999 and up Vortec, that would be an LS) then theoretically you could achieve similar fuel mileage. Fuel injection should go a long way towards getting good gas mileage and having good driveability.

Assuming fuel mileage is a function of motor, transmission, rear end gearing, and aerodynamics, you could replicate many of these in the old truck.

Lol I’ve driven the sm465 and was worried that the nv4500 would only be a mild upgrade from that. So now you got me pumped for this thing. Sounds great for my needs.
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[Woody2shoez]

Originally Posted by HO455

One way to decide if you want a NV4500 would be to go test drive a used truck with one. That would give you a basic idea of what to expect.

Great idea
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[WhiteCST]

Honestly I don’t think it’s too difficult at all. All it requires is different engine mounts and a new wiring harness, which to me is the most difficult unless you buy a pre made harness such as painless. Then it’s as simple as finding the adapter parts iou need for your current trans, or source a transmission such as the 4l60e that’s intended to be with that engine and then it’s all plug and play. The new transmission will require alteration to the old trans x member, or they have new bolt ons ready to go. There’s an awesome write up on this site where a guy swapped his for very low $$$. Here’s the link: http://67-72chevytrucks.com/vboard/s...d.php?t=517347

[WhiteCST]

I’ve helped with one and am currently doing my own. No swap is easy but this one isn’t too bad at all.

[Woody2shoez]

Originally Posted by WhiteCST

Honestly I don’t think it’s too difficult at all. All it requires is different engine mounts and a new wiring harness, which to me is the most difficult unless you buy a pre made harness such as painless. Then it’s as simple as finding the adapter parts iou need for your current trans, or source a transmission such as the 4l60e that’s intended to be with that engine and then it’s all plug and play. The new transmission will require alteration to the old trans x member, or they have new bolt ons ready to go. There’s an awesome write up on this site where a guy swapped his for very low $$$. Here’s the link: http://67-72chevytrucks.com/vboard/s...d.php?t=517347

Thanks dude
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[WhiteCST]

Not a problem! Any other ls questions feel free to pm me, I’ve done A LOT of research and have some really good hands on.

[MARKDTN]

Instead of FI Tech, would you consider a GM Tuned Port? They were available with 700R4 and parts are cheap for them. Visual appeal is awesome as well as the low-end torque.

Basic 350 roller-cam crate motor from GM is like $2000, a used TPI say $250, Harness ECM and PROM say $500-600, set of injectors $200. Then a 700R4 from a reputable builder say $2000. Fuel pump say $150. Then radiator, springs, driveshaft mods, automatic column, engine mounts, misc add another $1000. You could stay under $8k and do the mods. You might even have enough there to get disc brakes (which with the crossmember could also get you later V8 mounts)

I have a '90 Corvette TPI engine in my '83 K20 with 3.42 gears. It is a night and day difference from the 350 that was there. Mileage jumped from 14ish to 18ish. It is so much nicer pulling hills than the carbed engine was.

[Benjamin]

Originally Posted by MARKDTN

Instead of FI Tech, would you consider a GM Tuned Port? They were available with 700R4 and parts are cheap for them. Visual appeal is awesome as well as the low-end torque.

Basic 350 roller-cam crate motor from GM is like $2000, a used TPI say $250, Harness ECM and PROM say $500-600, set of injectors $200. Then a 700R4 from a reputable builder say $2000. Fuel pump say $150. Then radiator, springs, driveshaft mods, automatic column, engine mounts, misc add another $1000. You could stay under $8k and do the mods. You might even have enough there to get disc brakes (which with the crossmember could also get you later V8 mounts)

I have a '90 Corvette TPI engine in my '83 K20 with 3.42 gears. It is a night and day difference from the 350 that was there. Mileage jumped from 14ish to 18ish. It is so much nicer pulling hills than the carbed engine was.

That's what I'm talkin' bout!!!

I see you are in TN. Are you planning to go to the GM truck show July 14?

[dave`12]

You probably not interested, but consider this:

You could get a carbureted turnkey crate 350cid for 5k with a warranty. Now keep your sm 465, which is a great transmission, or if you want automatic, go with a turbo 350 or turbo 400.

This combo would be powerful, reliable, and much simpler than what you are looking at now. Then, with all the money you save, you could lower the truck, add disk brakes, a/c, etc. and still come in under budget.

This would be a much easier install, I just put a 350 in place of my 250 with a friend not long ago. The wiring alone will be a ton of work on your FI/700r setup.

[WhiteCST]

5k for that is insane when you can get near brand new LS1’s for less than that. Gen 3 irons are a fraction compared to that even. Never understood how crate motors can be that expensive and sell. 5k is a low mile 6.0 and 4l80e installed, and money left over. Now that’s a lot of power and reliability for your dollar not to mention pretty good fuel economy. Especially in a 3/4 ton