A 2wd box will work but they are weaker, won't accept aftermarket pitman arms with out some grinding (and then only certain years), mount differently to the frame, and might possibly have a different amount of throw. HOWEVER, if you were in a bind, and could not find a 4x4 power steering box, you could mount the 2wd up and make it work no problem. I've seen it done several times. It's just not as elegant a set-up as using the IFS box.
