It's not too hard, even I can do it! Put it on jack stands, drop the driveshaft, remove rear wheels and brake drums, 5 nuts on each side let you pull the axles out a few inches, loosen the nuts on the third member to let it drain the lube, then pull the third member. Clean the housing, put a new gasket on, and start reassembly. Don't forget new lube, and to check the end play on the axles.
See how easy that was? lol (quick reply, so I probably forgot something, so check a manual).
Dallas