[corning_d3]

That sounds like the differential going south. There are a few tools you'll most likely need. You'll also need to have some knowledge about pinion bearing preload specs, and how to properly shim the differential case, etc. I think a good chiltons or haynes manual should point you in the right direction if you choose to do it yourself. If you want it to last a long time, however, I'd suggest taking somewhere where you trust the mechanic/technician.