Getting greasy is half the fun.
But with any rear end that is "new to you", you would want to pull it apart, including the axles, to check the bearings and shafts for excessive wear. Better to do this in a salvage yard before you take it home than to have your "better half" get upset over the "Valdeze spill" on the driveway. Just be sure to catch the oil before it hits the ground as most of the newer yards get upset as well and may ask you not to return.
