Does anyone know if you could take a 58'-59' Chevy Apache...remove the front end (hood, fenders, grill) and simply replace it with parts from either a 55', 56', or 57' - without a hitch?

Also....what about the 3200 series 1956. Cab, fenders, hood, and grill look the same as the 3100's, but does anyone know if they are actually interchangable - making the "bed" size the only difference between the 3100's and the 3200's.

Yes the front clip will fit. All of them all the same for the most part. There are a few differances with the fenders but it will all be workable.