POWER TRAIN
Some GV70 (JK1, JK1A), GV80 (JX1) and G80 (RG3) vehicles may have a hum or whine noise condition from the rear differential at certain speeds. This bulletin describes the procedure to inspect the vehicle for the hum or whine noise and, if necessary, to tighten the rear differential lock nut to specification. If the hum or whine noise remains after tightening the lock nut, then this bulletin provides instructions to replace the rear differential or other driveline components as necessary.