GM 14 bolt 9.5" Eaton True Trac Posi. 33 Spline, rebuildable & very durable. Fits 79-2013
 
The True Trac limited slip uses a worm-gear design to bias torque from one tire to the other, providing extremely smooth operation. Since there are no clutches in this unit, there are no parts to wear out and no need to run limited slip additive in your oil.