This is an aftermarket Chrysler 8.75 limited slip differential. 30 spline. Came off a 1966 A-body. Chrysler Mopar Power-Lock Posi Unit - 30 Spline. 8-3/4" Sure-Grip Posi Unit Clutch-Style Unit positraction for Chrysler. It uses a two-piece case and six forged internal gears. Two years old with very minimal wear in excellent condition. Upgraded to the Torsen worm gear style. Don’t need this one anymore. $250 or best offer. 760-626-486zero