I'd try to find out why it doesn't in engage? What happens when you try and put it in 4lo?I just fixed one last week where the linkage came apart under the boot/tcase lever. Pretty easy fix, but probably not a very common problem. Christo was there and mentioned hearing of the pin coming out on others, but this was the linkage just below the tcase lever. The entire frame had been replaced on this particular 100, so that may have had something to do with it. (reassembled incorrectly)
Wheel bearing repack is about $350 per side, but isn't that hard of a job. It's about $70 per side if you do the work yourself and replace everything. Should take a few hours.
Rear locker could be an actuator problem from not being used. Can be taken apart and cleaned or replaced (if it's not working)