For the syncros to line up, the Powertrax components fit together in just one orientation. We marked the couplers and driver halves with a marker in the correct orientation so we could visually confirm that the pieces are correctly installed. The couplers slide in place of the side gears and use no thrust washers in this application. The C-clip on the left-side axle is now installed. The driver half is fitted with springs and the spacer, and is then slipped in to engage the coupler. If the all parts are oriented as specified in the instructions, the teeth of the driver and coupler will seat together.