Just take it in to your Cadi service and tell them the rear diff is whining like a lil bitch. They will throw it up on the rack and the tech will verify it. If he agrees, then they replace it. Its that simple... Oops did I actually just say that dealing with Cadi service department is simple?? HAHAHAHA, wow I just told a lie. Now seriously, just take it in and let them deal with it.