Well the rear axle out of a 4x4 will be 6 lug, should be a direct swap. In your case a similar year (or essentially any) 10 bolt from a 1/2 ton 4x4 should do the trick. As far as the front, I've never had a full size truck that was 2wd, but would have to assume that it should be easy to just grab some 6 lug hubs from whatever is compatible, not sure though, pretty sure even the C/R20 would've been 8 lug. Not sure what swapping that out entails or how simple/difficult it would be, I've never personally looked closely at a 2wd square. I've seen 67-72s and 2nd gen S10s, those are about the only 2wd trucks I've ever been around. Heck an aftermarket option to swap from 5 to 6 lug might be something that's readily available but I just have no experience, never had any reason to mess with 2wd stuff. I'm sure someone will chime in soon, there are plenty of guys here that know way more than me.