Yukon Gear and Axles Trac-lock positraction limited slip differential provides smooth yet aggressive traction to give you the confidence and performance you need in a variety of terrains. The Trac-lock posi limited slip is engineered for long life, and is completely rebuildable. These are built with a high strength nodular case and forged 4320 chrome-moly spider gears, and Raybestos composite clutches for long life.  The Yukon Trac-lock: for unmatched posi-traction performance.