I have a 1991 mustang lx 5.0. It has developed a clunk noise every once and a while in the rear of the vehicle. I have checked the universal joints and they are tight. When I rock the car back and forth in park I can hear the noise every now and then. It also does it when I take off from a stop. It is a pretty audible clunk. I had my brother look underneath it when I rocked it back and forth in park. He said he sees the whole rear end shift forward and back. That does not seem right to me. I do not think it is supposed to do that. Let me know if anyone has had a similar problem with theirs. Also throw some stuff out their I should check. Please help. Thanks Travis