Well the upper rear hydraulic shock mount could be loose or worn. It is just a pair of rubber bushings. Maybe diff mount. You will have to get in there and look around.
If your front end has never been done, it is probably well past time. Chances are you need lower ball joints and guide rods... well that means you have to dismantle pretty much everything so you should just go ahead and do lower control arm bushings and upper arms. Sounds horrible, but it is not. I can do a front end in a few days now.
