Hey I currently own an 83 F-350 6.9 idi 141" DRW 4spd 2x4 cab and chassis which I want to restore and make into my welding rig. The idi's cab is pretty much shot, the frame has some rusty spots which I am comfortable in my welding/fabricating abilities so I think that's totally fixable. I also own an 85 F-250 HD 351w 133" SRW C6 auto 4x4 which I bought from the original owner. They took good care of the 250, cab is in really good shape no cracks in the dash if you can believe it rockers, cab floor, and cab corners are all in perfect condition. Now here is my dilemma I really don't want to go thru the trouble of fixing the cab on the 350 which is the truck I really want. How much of a PITA would it be to swap the cab over and possibly converting the 350 to a 4x4 and using my 250 as a complete donor truck. Both are single cabs non AC trucks. How much of a problem will it be swapping from a standard to a cab and chassis. Will the 250HD front axles be beefy enough to go onto the frame of the 350. Look forward to hearing what you guys think if this is doable or just a dumb idea.

 

Its doable, but a pain in the ***. I converted my '88 F250 from 2wd to 4x4. It took a lot of planning and measuring, and quite a bit of work.
If you are a good welder, that is a plus, as the front of the frame is different between the 2wd and 4x4. You will need to swap over/fab brackets for the front suspension. 2wd used coil springs, 4x4 used leaf springs. The shock mounts also need to be moved over (2wd shocks mount on the coil spring bracket. Steering linkage and pitman arm will also need to come over from the 4x4.

You will have to look into the front axle a little more to see if its worth using it. I believe there are a few options for the gassers, and it may not be heavy enough for the diesel. If its a Dana 50 TTB it may be ok, look at the size of the hubs to see. A Dana 44 would NOT be a good choice. Being an F350, and a diesel, and going for a welding rig, which would likely have a lot of weight in the bed... You may be better off getting a solid axle Dana 60. Seeing your truck is a DRW, having a dually front axle is a smart idea, as all the wheels would be same (instead of dually rears, and single fronts). Good news is its easier to find a dually Dana 60 than the single wheel version (basically the same but the hubs are different).

Swapping the cab is a good idea if your cab is shot, but it would be a waste of a good truck to part it out if the frame on the F250 351 is in good shape, especially since the front axle may not be the best for your truck.

 

it would be much easier to just swap the engine into the 4X4 frame than it would be to 4X4 swap the two wheel drive frame