Positraction chatter is normal for limited slip and positraction differentials. Both rear tires must measure the same height from the ground to the top of the wheel in order for the differential to function properly without premature wear. Limited slip additive or friction modifier for limited slip differentials must be used with the oil to reduce postraction chatter in the event that the oil is changed.
Mechanical locking differentials will bang and clunk during normal operation. Both rear tires must measure the same height from the ground to the top of the wheel in order for a locking differential to function poperly.
Rebuilt #53 Powerlock, Used good case, Used good gears, New disc kit. Includes limited slip additive – $700
To understand more about the Powerlock differential you can visit the Willys Motor Service Bulletin no.500 here: