My truck has developed a very annoying hollow-sounding thunk/rattle whenever I hit a sharp bump (pot-hole, railroad track, manhole cover, etc.). Sounds like it's coming from directly under the back seat. I have been under the thing 10 times now and can't find anything loose or hitting the frame or cross members. It's got relatively new Bilstein shocks (35,000 miles) and the ball-joints and track bar bushings have recently been replaced. I'm starting to suspect a suspension bushing of some type, but I have to get the thing up off the ground to see.

Anyone have some ideas?

 

I case anyone is interested, I found the culprit. I had to take it to a garage and put it on a frame lift to unload the suspension. The link pin that connects the anti-sway bar to the axle on the drivers-side was broken off inside the ball-and-socket cup. It was the 2 ends rubbing over each other that was making all the racket and transferring the noise through the frame. Replaced both link-pins (the other one wasn't much better) with MOOG greaseable units and everything is back to the way it should be!

 

good deal!!