Are you rubbing on the inner fender/mud flap/ect? There should be no "gear slipping" noises coming from the diff. Even with chipped teeth, there is no way for it to skip gears.

It might need more LSD additive. Some need more, even if the gear oil has it included. Go do some tight turns in a parking lot and listen. It will chatter if there is not enough.

Good Luck,
Michael