Sorry if this has been covered already, but didn't really see what I was looking for in previous posts. My 05 GXP has terrible thumping noise in rear, so I assumed it was the struts and/or mounts. I have Bilsteins. When I took it apart it looked as though the mount was fine, but can't really tell whether the strut is shot. I'm just wondering if maybe the top nut came loose on each side?