[Big Block Bill]

Steve

You can try draining all the fluid again, re-filling with the proper synthetic gear oil, and adding a bottle of GM Limited Slip Differntial additive or Ford Friction modifier. It was a must when servicing or overhauling the ZF 5-speeds found in Ford Trucks from the 1990's. We also have had to use this process in the Mustang 5-speeds and GM 14 bolt rear differentials with posi "Chatter" on the 3/4 ton Suburbans, Pickups, and 1 tons. It is a cheap fix to a potenially expensive problem. I hope this helps.

Bill