Project "CREWMAX" Just another crewcab build....
 

Finally decided to post my build thread.

71 4x4 Crewcab Longbed with Duramax/Allison Power Train

Cab is currently at the body shop getting the extension treatment. Hope to have it back by May or so.

Just picked up a 2002 Duramax for powertrain, interior, etc..

Have a couple immediate questions

1. Should I use a factory 71 Chevy 4x4 Frame and just extend it. Worried about the strength? Could box the entire frame. Using that frame would require building all new mounts for everything.

2. Use a 2001 or newer HD frame, everything would bolt in and just re-do the cab mounts. Am really worried about how much of the frame would be seen as those trucks seem to have a ton of frame showing below the cab and it looks like crap. Maybe I could lower the cab as mush as possible.

3. Couldn't I use the 2002 factory wiring harness and just splice in everything, lights, etc..... Plan on using the factory dash, steering column etc..

Any one have any pics of these bodystyles on newer frames

Re: Project "CREWMAX" Just another crewcab build....
 

No thoughts or comments?

Re: Project "CREWMAX" Just another crewcab build....
 

Like it. I'm almost done with a frame swap and with all the searching not many had positive thoughts about swapping the frames. The biggest concern was all the alignment of the new body mounts, the wheel base, etc. My thought is if you're daring enough to even think about this swap then fabing up body mounts is the least of your worries. I would think the stock frame is way too flimsy then a fully boxed newer frame. As for the height of the cab I got creative with the frame height and the cab floor, sits very low now, almost too low for the AWD. Looks like a great project.

Re: Project "CREWMAX" Just another crewcab build....
 

Nice

Re: Project "CREWMAX" Just another crewcab build....
 

Sweet project you are building! My thoughts on a frame swap from a newer GM truck is they look ugly, and out of place under these trucks. (This is just my opinion) They can be made to look ok by hiding it with some step tubes and stuff, but still not ideal. My personal opinion is to start with a cab and chassis 156" chassis or a C30 133" chassis and stretch it to fit your needs. These are the heaviest pick up frames and will take the torque and power. Boxing can't hurt but is some additional work.

Here is one I saw the other day. I just can't get over seeing the entire frame under the truck.
https://www.youtube.com/watch?v=mA9TZC4vsX0

Here is a build thread of another one I remember.

http://www.competitiondiesel.com/for...hlight=duramax

Re: Project "CREWMAX" Just another crewcab build....
 

Very cool.

This guy did just what you want to do (but I think it was a 1999+ 1500 Chassis). Frame swap starts around page #9

http://67-72chevytrucks.com/vboard/s...hlight=FRANKIE

Re: Project "CREWMAX" Just another crewcab build....
 

That's not really a good comparison. He's wanting to use a HD chassis, not a 1500. From everything I've seen, the HD frames have more droop under the cab than the 1500's.

Re: Project "CREWMAX" Just another crewcab build....
 

Continuing to watch all those videos and still contemplating but I am leaning toward just using the older style frame and boxing it. Much cleaner look in the end I believe. Now to just decide if I should use the 1/2 ton frame or find a 3/4-1 ton frame. Anyone know the specs differences between them?

Re: Project "CREWMAX" Just another crewcab build....
 

Thanks guys for the links above, now to make some decisions and get my body guy moving on the cab!!!

Re: Project "CREWMAX" Just another crewcab build....
 

My neighbor built a '68 GMC regular cab on a 2006 2500 HD chassis.

IIRC, lowering the cab to cover more of the frame wasn't terribly difficult but lowering the bed would've required raising the bed floor if he used a standard bed. (he didn't) I'm not sure how adding the crew cab would affect the ability to lower the cab either.

Anyway, it might help you get some more ideas.

He posted a series of u-tube videos about the conversion.....

Here's part 10 Frankentruck HD

Re: Project "CREWMAX" Just another crewcab build....
 

Pick - That's funny, I watch about 6 or 7 of those last night around 10:30 or so after some of the guys above gave me a few different links. I have a bit to decide but am on the look out for both frames at the moment. Really like the idea of the older frame but do believe it would be nice to start with a 3/4 or 1 ton as I am sure they are taller/thicker and a little beefier. Will be doing some investigation this weekend between crossmember sizes etc..... Might just box the old frame and see about using the factory crossmembers if they are wide enough? A lot to ponder....

Re: Project "CREWMAX" Just another crewcab build....
 

IMHO for building a period crewcab with an 8' or 8 1/2' bed the best choice would be a hybrid frame using a 157" C30 frame and splicing in a C30 133" rear to maintain the factory top line thus a facory bed installation.
As to reference numbers this is my latest frame specs blurb.


The 67-72 frames are not exactly the same except the K10 LWB and K20.
These are the different PICKUP TRUCK frames as I understand.
Referenced from the GM 1970 truck engineering specifications book.
Any corrections are invited.
SS Tim

C Blazer COIL
C/10 115" COIL
C/10 115" LEAF
C/10 127" COIL
C/10 127" LEAF
C/20 127" COIL
C/20 127" LEAF
C/30 133" LEAF (Longhorn C/20 & C/30, 9' Stepside)
C/30 157" LEAF (Chassis Cab only) included for reference
Note: The 157" frame kicks up a little higher than the 133" going over the axle and does not drop back down like a 133" or 127"


K Blazer
K/10 115"
K/10 / K/20 127"

The frame section and modulus numbers, 39k psi carbon steel through C30s. Note the increased section height, flange width and thickness changes of the frame as the series step up.

C Blazer
C10 115"
C10 127"- 6.04" section height, 2.53" flange width, 0.156" thick, 2.98 section modulus

C20 127"- 6.11" section height, 2.46" flange width, 0.194" thick, 3.71 section modulus

C20/30 133" (Longhorns)- 7.20" section height, 2.77" flange width, 0.194" thick, 5.05 section modulus

C30 157"- 8.18" section height, 2.97" flange width, 0.224" thick, 7.29 section modulus


K Blazer
K10 115"- 6.02" section height, 2.71" flange width, 0.141" thick, 2.70 section modulus

K10 127"
K20 127"- 6.09" section height, 2.75" flange width, 0.186" thick, 3.48 section modulus



http://67-72chevytrucks.com/vboard/s...95&postcount=5
http://67-72chevytrucks.com/vboard/s...2&postcount=12

Re: Project "CREWMAX" Just another crewcab build....
 

SS TIM - Man cannot thank you enough for all that info.... That is some great information and a lot to digest.

I do believe I see your point in using a 157'' then splicing the 133'' rear section but looking over the info below I am curious if the 157'' frame eventually tapers to the same section height of the 133'' at some point???

Utilizing the 157 would give the crewcab plenty of flat frame section then the 133 would allow a long bed to match up nicely with the correct step up.

As far as boxing a 1/2 ton frame, would the section modulus double in that regard?
While boxing the frame does take some work, finding two separate frames could be pretty difficult also.

Thanks, appreciate all the input

Re: Project "CREWMAX" Just another crewcab build....
 

Hope it all helps and isn't TMI!
As to the matchup, I don't have a full profile map of either frame to say for sure but it may very well be close at some point.

Given the thickness of the flanges on paper it looks like the 133" frame will be about 0.53" shy of nesting inside the 157" at full section height. To me, nesting against the top flange and pie cutting the lower flanges would be the solution. Then finger tabbing the upper and lower flanges as runouts.
Here is a thinking out loud sketch.

Boxing or section increase is your choice but I think using the taller factory section and selective plating/fingering/boxing is probably best.

Re: Project "CREWMAX" Just another crewcab build....
 

Last I knew, Cypressbog in Wisconsin has a 133" frame and cab he's trying to sell. I had a line on 2 157" frames but I guess the guy scrapped them. A day short on that.

http://www.67-72chevytrucks.com/vboa...d.php?t=718852

Re: Project "CREWMAX" Just another crewcab build....
 

this should be an interesting build ..

Re: Project "CREWMAX" Just another crewcab build....
 

I'm in! Done yet? :lol:

Re: Project "CREWMAX" Just another crewcab build....
 

Thanks Dieselwrencher I sent him a PM about it

Re: Project "CREWMAX" Just another crewcab build....
 

What about a C50 frame? Do they have the same body mounts for the cab/front clip? Just curious because there have been a few I have seen for sale. Just Curious

Re: Project "CREWMAX" Just another crewcab build....
 

I am not for sure, but I think the C50 frames are more of a C channel frame. You could probably use it. I'm planning to on my next build. Hopefully :lol:

Re: Project "CREWMAX" Just another crewcab build....
 

I have a 1972 C50 that is from SD that I would sell the frame off if you decide to go that route. I think it is a 157" wheel base.

Re: Project "CREWMAX" Just another crewcab build....
 

Looks like the C50 frames are mostly flat, I think I'll pass on that option.

SSTim - you mentioned that the 157" frames kick up higher over the rear axle than the others, any idea how much additional? As this will effect the final bed height and might require me to shim the cab higher to match the body lines. Any idea of that measurement?

Thanks guys

Re: Project "CREWMAX" Just another crewcab build....
 

Yes, I posted this link,
http://67-72chevytrucks.com/vboard/s...95&postcount=5

along with the data I have in post#12
http://67-72chevytrucks.com/vboard/s...2&postcount=12

Re: Project "CREWMAX" Just another crewcab build....
 

Cool build!! What is the biggest challenge to get the body lower on the 2500 frame? Width of the frame or the shape?

Re: Project "CREWMAX" Just another crewcab build....
 

Love me a duramax swap, and a crew too? Dream truck.

Re: Project "CREWMAX" Just another crewcab build....
 

Man its been a long time guys............ BUT good news - project is back on the front burner. Body shop is doing their thing and I am starting to gather parts again.

Just picked up a 2005 Ford F250 complete with Dana 60 front, coil springs etc.....

PROBLEM - Where we left off above was frame selection - I couldn't make up my mind and was concerned with using a 1/2 ton frame -

SOLUTION - I picked up a 72 Chevy C-30 Cab and Chassis

NEW PROBLEM - As SSTIM pointed out the frame does not drop back down and is 2'' higher where the bed mounts vs. 1/2-3/4 ton frame. This would result in raising the cab mounts or a bod lift - I AM OPPOSED TO THIS AS I REALLY DONT WANT TO SHOW MORE FRAME THAN NECCESSARY.

SOLUTION - Use the c-30 cab and chassis frame I have, shorten in the middle (flat section). THEN - cut 2'' out of the rear top frame section and box that back in with a C -Channel

Someone shoot holes in this plan or give me your thoughts. I am open to suggestions. I really just figured all this out this morning and am still pondering other ideas.

Re: Project "CREWMAX" Just another crewcab build....
 

I think your plan sounds pretty good. I'm wondering, where the frame kicks up and is higher, could you cut the frame and take enough material out to get the 2" drop needed? Then sleeve and plate it? It should ride really nice with the coil springs in front. Weren't all D60s in the fords starting in 05 and up considered Super 60s?

Re: Project "CREWMAX" Just another crewcab build....
 

Not sure on the "Super 60" I do know that the 2005+ Dana 60's are some stout pieces for sure. And a smoother ride is exactly what I was shooting for since this one will be sitting up and riding on some 37''s.

FRAME UPDATE - I might have tracked down a guy fairly local that has two c20 frames. If that is the case I might go that route. Splice the two and not have to worry about cutting the rear end of this one down.

Any crewcab projects out there that can give me an exact dimension to cut this thing? I can wait till the cab is done, then bolt it on, rough set the bed and then cut but would love to cut it all before hand. Anyone have a good dimension??

Re: Project "CREWMAX" Just another crewcab build....
 

Everyone loves pics - Here are some of the body work currently ongoing

Re: Project "CREWMAX" Just another crewcab build....
 

just raise the box floor itself enough to get your clearance? box sides stay the same. 2" won't make much of a functional or visual difference

Re: Project "CREWMAX" Just another crewcab build....
 

t300 - that is why I love this page, didn't think of that option. Will have to ponder that a little

Re: Project "CREWMAX" Just another crewcab build....
 

You are the one building it, you can do what ever you want to get the look you want. I vote rise the floor.

Re: Project "CREWMAX" Just another crewcab build....
 

Alright frame problem is solved..... when shortening will remove section out of the step up area to reduce the height by 2'' or so... then will remove remainder of length out of the middle flat section of frame.

Couple pics of the current body work

Also looking for a roof skin with cab light humps? Let me know if anyone has one ( I have posted in the classified section fyi)

Next up on the agenda
1. finding a good drivers side suburban door
2. find marker light roof skin
3. deciding on seat selection - probably will use the factory 2002 front bucket seats but not sure if the extended cab seat will be big enough or if I need to run a full size rear seat.

Re: Project "CREWMAX" Just another crewcab build....
 

pics

Re: Project "CREWMAX" Just another crewcab build....
 

sitting on the 2wd frame, mocking up new cab mount locations

Re: Project "CREWMAX" Just another crewcab build....
 

Looking really nice!

Re: Project "CREWMAX" Just another crewcab build....
 

It's coming along! It always stunk working on it before having a frame under it.

Re: Project "CREWMAX" Just another crewcab build....
 

couple updates

Frame has been shortened and rear sectioned/ lowered for bed fitment.....she is a roller. Too bad all the suspension gets replaced. But it is moving along. Also was able to snag a marker light roof panel that will be grafted into place.

Re: Project "CREWMAX" Just another crewcab build....
 

another

Re: Project "CREWMAX" Just another crewcab build....
 

That is looking great and coming along really fast!