The reason I brought this up was because of the gear ratios that Toyota used in the 4x4s. The lowest ratio used was 4.10 (maybe 3.90, but its still low). The rear would be easy, just swap in a 2wd rear end. The front would be tricky though. You could do like Rockwell said and swap in a solid axle. Without the swap, you will be limited to low gear ratios and high(er) cruising RPMs. The higher RPMs may not be an issue though.
http://home.4x4wire.com/erik/diffs/
This site claims the front diff in the 4x4 uses the same internals as the 2wd rear end. If so, then the solution is easy. You could run any gear ratio that came in the 2wd trucks.
http://home.4x4wire.com/erik/diffs/
This site claims the front diff in the 4x4 uses the same internals as the 2wd rear end. If so, then the solution is easy. You could run any gear ratio that came in the 2wd trucks.