I just bought a 79 crewcab 2wd I was wondering if I could just put the crew cab body on the extra cab frame I already have a 78 supercab 4wd that I'm planning on using as a donor. So the big question is do I have to stretch the frame or what would be the easiest (best) way to go?

 

What is the difference in the wheelbase of the two? If you wanted to make it look original then you would need to stretch the frame super cab frame.. But if I was you, I would get some measurements and shorten the bed accordingly.
Your other option would be to swap the 4x4 running gear under the 2wd frame. (Lots of work but probably more practical than stretching the frame.) both will involve a fare share of fab work

 

Is the crew cab a long bed or short bed?

Either way I'd put the crew cab cab on the supercab frame & shorten the bed. It's a bit of work and not for the novice for any means though.

 

I think another site that begins with F and ends in ification has builders sheets or something like that that have all the frame specs. I found them for my 72 CC so maybe the SCAB's might be there also.

 

CCSB=150"
SCLB=155"
So, if you swapped your CC onto a SC frame, a shortbed is too short and a longbed is too long. Not that it hasn't been done, however. Here's a sweet one:
77 ford crewcab • Projects - Images and stories, etc... • Old Ford Crew Cab Community

 

Link is bad.

 

The whole site is down right now i think. I tried getting on a couple different ways but no go.

 

ok. Will just have to try back again later to look - thanks.

 

both are long beds I really want to keep it a long bed I am getting the truck tomorrow then I can measure up and see what would be the best. I'm thinking about stretching the frame as long as I beef up the section I lengthen. I should be able to cut from the 2wd frame and put it in my 4wd frame without to much issue right?

 

Personally I'm not a fan of frame stretching - or even frame shortening for that matter, unless it's on a truck that will be full caged from bumper to bumper & the cage will make up for any weakness caused by the frame cut.

There are guys who do it though and most of their trucks haven't broken in half yet. IF you decide you want to cut the frame make sure a qualified welder puts it back together & that the thing is properly fish plated & reinforced.

 

if your truck is a true 79 longbed 2wd then its alot easier to doa 4wd conversion usig the supercab parts than to do all the frame work. Im looking at making another crew purchase in the next couple weeks and i hope to do a writeup on it.

 

yeah I'd agree with that, its not that hard to make a 2wd a 4wd, especially if you want to lift it up enough to clear the crossmember. Then its really easy...