Mike,
if you can put carrier bearings in & shim the preload, then you can do it. Pretty straightforward carrier swop. You do have to drill the case for the air supply line & (Memory is struggling here <img src="/ubbthreads/images/graemlins/crazy.gif" alt="" />) the one carrier bearing cap to plumb the air supply to the carrier. Degree of difficulty is about the same whether you're doing the front or rear axle.
Gimme a shout on my cell.
badger