My friend is having probs with his rear end on his atv. He says there's a hollow knocking coming from somewhere in the back end. He said he replaced all the bearings in the back end and also the rear brakes. He also said he replaced something on the sway bars in there rear end(if there is any). I said it might be the diff. The u joints are still tight. If anyone has experienced the same probs or might have an idea what to look for I would appreciate the help thanks