Rear Differential Trac Loc with Aggressive Design (YDGF9-31-AG) by Yukon Gear and Axle. Steel clutch plates, half of which are covered with a friction lining material, are sandwiched behind the differential side gears inside the carrier housing. These plates are alternately tabbed to the carrier or splined to the axle shaft. The tabbed pieces are called plates and the splines are called discs. The side gears are preloaded with springs placed between the side gears. This preload provides greater traction to both axles. In a turning situation, the Dura Grip allows a speed differential mostly because the torque loads will be low enough to allow the differential to operate.