It is entirely doable, and easy. I have a 1980 4wd truck. The original cab was bad, and I replaced it with a 1974 2wd cab. Everything was a straight bolt-in, with the exception of the tranny tunnel floor. My truck is a stock 4 speed, the 2wd cab had an automatic in it. In the 2wd cab, there were indentations of where to cut a hole, large enough so that the removable floor tunnel in the 4wd cab could be transferred to it. Instead of welding nuts on the bottom of the cab for the removable tunnel bolts, I used large sheet metal screws instead. Except for that fact, my job looks factory. Go for it!