I have the same problem. To be completely sure get under your car and literally push the diff up and down. If you can without alot of effort your diff bushings are shot. Your should also be able to see the bushings that failed when you push the diff up and down. Mine are the front. I ordered some ES Diff bushings and need to install them. Be sure to get the whole kit fronts and rears. it like 18 bucks from Z1. Hope its only that. Goodluck