Hello, I'm new to the site, and looking for a little advice. I've got a 75 crewcab shortbed, and wanting to convert it to 4wd. I just acquired a 78 excab longbed 4wd, and hoped to shorten it a bit and put the crew body on it. I've done some extensive searching on this site, and have seen it mentioned. I guess I'm looking for specifics, like where to cut the frame, how to splice, what about driveshaft, brake lines, fuel lines, etc; and does the conversion require a body lift due to differences in contour in frames. I've given this alot of study, and have my own ideas, but I would sure welcome any advice from someone who has done this. Thanks.

 

i have a 74 crewcab shortbox 4x4. had a 78 f250 snowfighter supercab 4x4. was thinking the same cut the frame & swap cab&bed after all was said n done i took the 60f and steering 4 crossover in the end i had 2 running trucks sold the 78 for the price of the parts 2 finish my crewcab. frames already have most of the holes youll need either way u go sure itll be bad keep up the thread

 

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There can't be too much difference in the length of the 2 frames, have you measured the 2 wheelbases? That is kind of a straight forward job, after you pull the 2 bodies it will be pretty obvious what you have to change. The only thing you have to be concerned with is the shape and dimentions of the 2 frames, holes don't matter they're easy to drill and the crossmembers can be swapped easily if they are different.

 

near as I can tell, the extended cab is 5 to 6 inches longer. I'm trying to decide where to cut and splice at. So far, the best place appears to be in front of the front gas tank. It looks like the crew cab may sit off the frame a bit, since the excab frame turns up where the rear of the cab will mount. wish me luck

 

I would check the Cab Mounts first. The Front ones should be in the same place, but the rear would be different I think.

I just done a Short bed to Long bed frame swap on a Ranger. I extended the Cab 8 inches in the process. I did have to take 5 inches of frame on the rear where the Bumper mounts. I did know this ahead of time, and was prepared for it. Much easier to alter the frame with no body on it. Here is what I done.

Using a Plumb bob, Duct tape it into place on the Bed side and center it with the rear axle. Take a measurement from the string to the rear of the bed, then from the string to the front of the bed, and the back of the cab. Just for reference in case you need it, do the same with the front axle. Do this with both trucks. Now you have good solid measurements to go by, and can figure out just what you have to do.

To measure placement of frame mounts like the rear cab mounts, another trick is to stretch a rope around the tires (if tires are all the same). Pull this rope as tight as you can get it so you have a straight line. Find a center point for the item in question, then use a Carpenter square and go off the straight line created by the rope, then mark this spot on the rope. Then go from your plum bob and measure it.

It may sound crude, but you would be surprised just how accurate you can be with this. Especially when your putting it back together again.

 

I took a 78 supercab also and shortened it for the crew/shortbed. But, I have since then bought 2 75 crewcab 4x4 shortbed frames that are nice. I will probably get rid of one and keep the other for a spare...Its in South Dakota...

 

I did a 4x4 conversion on my 79 F350 dually. I believe the front section of frame on your crewcab is the same. I stripped the F 350 frame of all the I beam suspension,
crossmember, shock mounts,steering box and brake lines. A friend who is a good fabricator helped me build a new crossmember similar to a 79 250 4x4 which is boxed and welded into the frame. All the rest of the welding and fab work is pretty staight forward. I used a 79 4X4 with a dana 60 for a donor truck and used just about every thing from it. I had to fabricate front leaf spring mounts and a new crossmember for the transmission mount. I did it this way because my F350 has such a nice frame I wanted to keep it as stock as possible. I don't have a digital camera but If you e'mail me with your address I could mail you some snapshots of the conversion.