this is personal preference. some guys run a dana 44, some a dana 60 from a one ton, some just grab a 1/2 ton axle from an older chev, put better axle shafts in it, and run with it. you can use the leaf springs and shackles from an older chev pickup (by older i refer to pre-1987, before chev went to ifs.) but it is required, as gotstylez mentioned, to match the front and rear gears. solid axle requires alot of cutting, grinding and welding, and your ride quality will suck, but for mudding and trails, can't be beat. converting to the ifs 4wd can be done, a little easier, but you may still need to cut and weld a bit for the brackets that hold the front diff in. the control arms will need to be swapped for the 4wd ones. basically, gut the front end off the 2wd drive and replace with the entire frontend from 4wd.