The easiest way to do this. Remove the T-case, front drive shaft, and front chunk. Pull out the front half shafts, and remove the outer stub from the rest of the half shaft. Then put the outer stubs back in place to hold the wheel hub assembly to the spindle. Install the 2wd trans into the truck, lengthen the driveshaft to the necessary length.
Nothing difficult, aside from the driveshaft work, your looking at maybe a days work.
---------- Post added at 07:18 PM ---------- Previous post was at 07:14 PM ----------
Your 95 has a 4l60e and the 89 has a 700r4. The electrical is going to be the tough part to tackle. I would part out the 89 for enough to get a 4l60e from a salvage yard. If you still want to go to 2wd, you can just grab a 2wd trans and driveshaft.