Honestly, I'm not sure on a Sub. I just know that when people put a truck cab on a Blazer frame they always need/want the crossmember with body mounts for the back of the cab from a truck, I'm guessing a Sub will have similar issues.
I'm not sure what year it started but around the late 70's Blazer frames went from being completely straight to spreading out wider about a foot or so in front of the rear spring front hanger, did Sub's also do this? That might be tricky for a truck bed too.
Also, a Sub frame is fairly level in front of the rear axle so if converted to a pick up I would think you'd need to use a fair sized body lift on the front bed mount
Yup, that's what I was getting at....
Suburban cargo area is only 5' long with the second row seats up. That's where the second row doors are. Burbs cargo area is 8' long when second row is folded down. The square body Burb has a 129.5" wheelbase which is 2" shorter than the long bed pickup (single cab) at 131.5". For the OBS Burb the wheelbase is stretched that 2" to be the same as the single cab long bed, but the frame and body mounts are still different because of the floorboards vs. cab and bed.
My family's had 8 Suburbans. I've worked on all of them, loaded and unloaded them, washed them....I know them well.
Before that, we had 3 square body pickups, all GMC half ton single cab longbeds.
the sub has a WB of 129.5" as you said, the crew cab long bed has a WB of 164.5, best i can figure is the Crew Cab Shortbed is 150.5". That is taking the CCLB WB and subtracting the 14" from the frame length as people do when shortening a CCLB. So my idea stems from wanting to use the Sub's 1/2 ton f/r suspension, the TBI 350/700R4 trans, the steering column, the rear mounted fuel tank and the brake system as well as the entire interior, doors, and the front clip. Seems more straightforward to swap the bodies vs all the drivetrain and all i mentioned above. Either direction i go the frame needs to be either shortened or lengthened. As long as the fab work is done right and properly reinforced, it seems thats a better way for me to go with less chance of f'n everything up as the sub is a running driving vehicle where 95% of everything works. Anyway thats my plan. I might even sell the 89 Crew Cab 2500 and just buy a bare crew cab body then i don't have as much to part out or scrap when i'm done. I'll only have a suburban shell to get rid of. The pics show the rear body mounts on the truck cab are inboard mounted on a crossmember. The other pic is a sub chassis where the body mounts are outboard of the frame rail. There is a long straight section of frame on the sub frame pic where it could be easily stretched under the cab and the rear body mount crossmember added.
