Squealing from the rear end.
 

I just put a used 8.8" rearend into my mustang. It was off a wrecked car that I am not sure how long that it had been just sitting. It has Richmond 3.73 gears. For the most part it is very quite but everyonce in a blue moon you can hear a spinning squealing sound. Starts slow and than gets loud and fast and than slows down and goes away. I can not do it on command. Pushing or letting off the gas does not change the sound. It only lasts about 15-30 seconds. Any ideas what is up? We replaced the fluid in the rear.

Sounds like a bearing problem to me. I would pull it apart and check it out before something gets messed up.

Later,

maybe try driving it right circles....and left circles to get the oil to the ends.

dont know if it will help but it cant hurt