Suregrip additive?

Mopar additive-
Is what I use. 4oz bottle from dealer is like $8.00. If you still get chattering after driving around and the rear gets up to temp- I add another bottle. Cone type rears like the one in my 741 case seem to need 2 bottles. I just use a good brand 80w90 gear oil. Napa or Castrol. If I don’t recognize the name I won’t use it. Never tried the oil that has it in the bottle already.