Well after much conversation with the folks at Royal Purple about their 80/90 gear oil being ok in a posi unit I have tested researched and figured out that it is no good. not no good as a quality product, but no good for the clutches. RP states they have slip additive in the gear oil and that should suffice. After driving the car for a couple hundred miles and having the binding and chatter in corners on the gas I drained the RP and put Valvoline 80/90 with a slip additive and it could not feel better in turns. Just an FYI to everyone out there. I have been told that syn gear oil is no good on a posi, but RP begs to differ, I beg to differ back now.