Rear end side to side noise

Ok, so I started to hear a noise a week or so ago when driving into a driveway or over speedbumps diagonally. It basically sounds like something is loose and makes a clunking sound in the rear end. I have a 3" suspension lift frome revtec and thought to look under the truck to see if I could spot the problem. I did see that both rear shocks were loose and could be twisted back and forth. Figuring this to be the problem, I took my FJ to 4 Wheel Parts here in Modesto and they looked it over and said the problem was some missing washers?!?  They said it was fixed and checked, didn't even charge me...  Happily I left and drove towards home... only to hear the same noise still at each turn on a bumpy road and driveway. FRUSTRATING.  I got home and took hold of the rear drivers side tire and shook my truck side to side and could mimick the same clunking noise manually from either side. Has anybody run into this before? It's almost as if the wheels are loose from the way it sounds and feels. ( I checked that just to be sure ) Any advice would be appreciated! I couldn't really get under the truck to check their work as it's been raining all evening...