Musclecarman, I just had the rear end replaced on my 21 as well, 10,700 miles. had weird noise/vibration between 71-77 mph. Was told the rear end was full of metal shavings when they inspected it. I purchased the rear diff brace, swaybar bushing kit, JXB inserts, and pinion bushings but haven't installed yet, car is still in the shop.