Cab and bed conversion

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BuckWildCustom

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Hi all, I'm building a truck for my dad as a thankyiu for helping me open my shop and I have a single cab 8ft bed 1978 K20 Sottsdale, is it possible to use the frame still but convert it into a shorter bed and a full size 4 door cab? I haven't found a straight answer, or do I need a different frame? Any and all help would be much appreciated
 

Scott91370

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Anything is possible but what will it entail is the real question.
I've never compared a shortbed 4 door frame to a longbed frame so I can't be of any help with that. If you could find the dimensions of the frames online you could compare them and sort it out pretty easily I'm sure. Maybe up in the Squarebody Reference Library section?
 

Bextreme04

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They are not the same. You will need a donor crew cab anyways... might as well start from a crew cab frame and cab, then transfer everything good from the pickup onto the crew cab frame. Its fairly easy to cut 14" out of the rear of the frame and the bed to make it a short bed crew cab.... its not easy to make the originally short frame match the crew cab mounts and the short bed mounts.
 

BuckWildCustom

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Okay cool, yeah I didn't know if it were possible, if I have to get a new frame, I will stick with the long bed, I just didn't know if the mounts would line up, I'll do some more research and compare the frames and see if I can fabricate it
 

Bextreme04

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Okay cool, yeah I didn't know if it were possible, if I have to get a new frame, I will stick with the long bed, I just didn't know if the mounts would line up, I'll do some more research and compare the frames and see if I can fabricate it

Anything is possible if you don't mind spending the time... but why would you? Time is money, and the amount of hours you would save in janky fabrication to get the cab to mount right and in line with the bed(which you would have to shorten anyways) is just not worth it IMO. You should be able to find a stripped crew cab frame and cab for a few hundred bucks... it shouldn't matter if it's 2wd or 4wd. Then just cut the 14" out of the straight section behind the front mounting bolts and weld it all back together. Now you have a short bed CC that will use all the factory mount points and line up just like stock.
 

BuckWildCustom

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That's true lol, yeah I would want it to be done right, so then when my dad takes it to car shows, it stays as close to classic as possible lol
 

Craig 85

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I had a an '80 C20 3+3 back in the mid 90's. From this forum I learned that even though it was a 20 Series truck it actually came with a 1 ton frame. The 30 Series frames are 2" taller than the C20 frame (8" vs 6" I believe). Definitely look for a 1 ton frame.
 

ak4life

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Anything is possible but what will it entail is the real question.
I've never compared a shortbed 4 door frame to a longbed frame so I can't be of any help with that. If you could find the dimensions of the frames online you could compare them and sort it out pretty easily I'm sure. Maybe up in the Squarebody Reference Library section?


Yeah good luck on finding that info, ive been building a single cab long bed on a different frame that i was told was the same but now im thinking its suburban and cannot for the life of me find exact info.....
 

ak4life

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You can do a lot with any GM.
Great trucks to work with.

Crew cab on Suburban frame below.

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They are not the same. You will need a donor crew cab anyways... might as well start from a crew cab frame and cab, then transfer everything good from the pickup onto the crew cab frame. Its fairly easy to cut 14" out of the rear of the frame and the bed to make it a short bed crew cab.... its not easy to make the originally short frame match the crew cab mounts and the short bed mounts.


Would you happen to know if a 81 1/2 ton single cab longbed 4x4 body will match up body mounts to a 84 3/4 ton 4x4 suburban frame ? squarebodys of course.
 

Bextreme04

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Would you happen to know if a 81 1/2 ton single cab longbed 4x4 body will match up body mounts to a 84 3/4 ton 4x4 suburban frame ? squarebodys of course.

I doubt it. I've never seen them side-by-side but I would be very surprised if the frames/body-mounts lined up at all.
 

Trixxterr

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Ambitious project to say the least, I think it would be amazing though. Mostly because of the story, reasoning behind it..
 

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