^^^ when you go over a bump and it makes a vibrating noise, is it a dull vibration, or a sharp sounding one?
when i needed new front dampeners, i would go over a bump and it would make a dull vibration. since the strut was dead, it was not doing anything and i was pretty much bouncing up and down on the spring and the strut was just following along. new struts fixed that.
push down on your rear suspension, get the car bouncing up and down pretty good. when you stop, it should rebound once and then come to its resting position. if it doesnt, you need new shocks.