How do you replace the ring and pinion in a amigo?

The problem is that I put lowering blocks in the back and after a while the u-bolts loosened about 6 months later I foregot to tighten them.This caused the differential to roll back and roll at a high pinion angle. The result being I now have to replace my ring and pinion gear because no fluid was getting to it. Any pics or web sites would be much appreciated