Re: 2wd to 4wd conversion
The 4x4 cabs and bodies have a clearanced floorboard for the transfer case, so a body swap won't work either. Just buy a 4WD with a blown engine or trans for a couple hundred $, then you can build the heck out of it! Or if you know your gonna do a SFA conversion, buy a 4cyl/5spd 2WD for cheap to use as a basis(Frame, body, etc). Whatever you decide, a 2WD to 4WD swap on an S-series is nothing less than a full-on Custom fabrication job to be done by skilled welders and fabricators.
1989 GMC S-15 4x4 4.3L/700R-4, 3.08s, 31" Sport Kings For Sale
1985 S-10 4x4 Soon to have 3504BM/TH350/D44/14FF, 35" Boggers