91 c3500 6.5/5 speed repower

[mamumtsllc]

So my uncle had this truck and I worked on the 6.5 in it. He passed away and the truck got sold at auction. They pulled engine and trans out and sold it. I found the truck and bought it back. Thinking of going dmax with Allison for simplicity and finding them easier. Truck is a crew cab 1 ton 2 wheel drive. So long as the day is. Would I be better off putting this body on a later frame? Or put the motor into this setup? Just looking for opinions and/personal experience. I want to make sure I look at it from every aspect.

Thanks! I'll try to get some pics of the old girl.

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[JoshH]

This is a regular 1 ton and not a 3500HD with the beefier frame/axles/brakes/etc than the standard 1 ton? If it is a standard 1 ton and not the HD, changing to a newer frame will be a good upgrade.

 

[mamumtsllc]

This is a regular 1 ton and not a 3500HD with the beefier frame/axles/brakes/etc than the standard 1 ton? If it is a standard 1 ton and not the HD, changing to a newer frame will be a good upgrade.

I think it's just a standard 3500. The HD had the bigger wheels and funky grille didn't they? Like the commercial truck? This is just like the normal pickups with 16" wheels.

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[JoshH]

I think it's just a standard 3500. The HD had the bigger wheels and funky grille didn't they? Like the commercial truck? This is just like the normal pickups with 16" wheels.

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Correct. The HD was only available as a cab and chassis also, so if it has a pickup bed, it is for sure not the HD.

 

[Chevy1925]

91 with the 6.5? late 92/93 was the first year for it.

being a C (2wd), you might have issues with the crossmember on them. i dont know how different the 2wds are from 4wd but i know they are coilspring with the pocket integrated into the frame. you might have clearance issues. you will have allison to body issues as well unless you put a 4l80 in it. the 14bolt rear axle will be ok. The cooling stack will take some modding to fit as its far taller than the original stuff in there.

 

[mamumtsllc]

91 with the 6.5? late 92/93 was the first year for it.

being a C (2wd), you might have issues with the crossmember on them. i dont know how different the 2wds are from 4wd but i know they are coilspring with the pocket integrated into the frame. you might have clearance issues. you will have allison to body issues as well unless you put a 4l80 in it. the 14bolt rear axle will be ok. The cooling stack will take some modding to fit as its far taller than the original stuff in there.

Yea I said 91 but I'm thinking it's 92 or 93 because it wasn't the pmd electrical pump. So its not 94 for sure.

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[TheBac]

This really sounds like a Fermanator question, doesnt it? If anyone will know, he will.

What -800 frame would work in this situation, anyway? I always wondered if this would be a straight (or close to straight) swap, as the -400 suspension parts/setup always looked very similar to their -800 cousins to me.

 

[JoshH]

This really sounds like a Fermanator question, doesnt it? If anyone will know, he will.

What -800 frame would work in this situation, anyway? I always wondered if this would be a straight (or close to straight) swap, as the -400 suspension parts/setup always looked very similar to their -800 cousins to me.

I assisted a friend with a body swap by putting a 95 body on an 05 frame. The wheelbase was close enough that the wheels lined up in the wheel wells pretty good. The biggest problem was the frame drops a lot more under the cab on the GMT800 trucks than on the GMT400s. If we had left it so the bed sat down on the frame at the back and the body lines carried forward to position the cab vertically, the entire frame rail would have been visible looking at the truck from the side. We ended up notching the frame for the bed runners to lower the bed and drop the cab as much as possible while still giving clearance for the rest of the stuff under the hood.

 

[mamumtsllc]

My other option would be to find a 6.0/4l80 (6l90) or even nv4500 and put a cam in it. Maybe turbo to just play with. I have other duramax trucks and semi trucks to pull with. So this would be a driver/haul kids around (since I have 3 and the wife wants another)

This option is appealing as the gas stuff is cheaper and a little less hard on the frames. Plus I've already done a swap into a obs truck so I kinda have that under my belt.

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[THEFERMANATOR]

91 with the 6.5? late 92/93 was the first year for it.

being a C (2wd), you might have issues with the crossmember on them. i dont know how different the 2wds are from 4wd but i know they are coilspring with the pocket integrated into the frame. you might have clearance issues. you will have allison to body issues as well unless you put a 4l80 in it. the 14bolt rear axle will be ok. The cooling stack will take some modding to fit as its far taller than the original stuff in there.

2 or 4 wheel drive doesn't matter, the DURAMAX/ALLISON combo has been dropped in with no cross member problems, no body lifts, no trans clearance issues(the ZF6 is a different story), the 14 bolt holds up just fine, but the Lb7/lly cooling stack does take some work to make fit in. Mine is 4x4, but several have also done 2 wheel drives. There is a facebook group that has probably 20 or 30 people who have done obs dmax swaps.

Now all of this said, I would body swap if at all possible. There is just no comparing the steering, brakes, and frame between a gmt400 to a gmt800.

 

[Chevy1925]

2 or 4 wheel drive doesn't matter, the DURAMAX/ALLISON combo has been dropped in with no cross member problems, no body lifts, no trans clearance issues(the ZF6 is a different story), the 14 bolt holds up just fine, but the Lb7/lly cooling stack does take some work to make fit in. Mine is 4x4, but several have also done 2 wheel drives. There is a facebook group that has probably 20 or 30 people who have done obs dmax swaps.

Now all of this said, I would body swap if at all possible. There is just no comparing the steering, brakes, and frame between a gmt400 to a gmt800.

good to know! thanks Ferm