For 1990-2009 cars

Checks | Action
--- | ---
Flat spot on the pinion or the ring gear teeth | Replace the pinion and the ring gear. Refer to Drive Pinion and Ring Gear Replacement .
Flat spot on the pinion bearing | Replace the bearing. Refer to Drive Pinion Bearings Replacement .
Worn pinion splines | Replace the pinion. Refer to Drive Pinion and Ring Gear Replacement .
Worn axle shaft dowel holes | Replace the axle shaft. Refer to Rear Axle Shaft Replacement .
Worn hub studs | Replace the wheel studs. Refer to Wheel Stud Replacement .
Bent axle shaft | Replace the axle shaft. Refer to Rear Axle Shaft Replacement .