[gregwils]

Lots of thoughts here, thank you all. I agree the compressed bushing is not the source of the noise, but I am hoping if I can determine what is causing the compression it may lead me to the cause of the clunk. Even if it does not lead me to the clunk, something is not correct in the vicinity of the noise so I feel like I need to fix it. The chassis sensor that I made tells me the noise is definitely coming from the t-bar or spring plate - new motor/trans mounts and noise exists with sway bar removed. Every single nut or bolt anywhere in the vicinity of the rear of the car is set to spec. I have examined the spring plate cover mounting bosses pretty closely, but it could be something not readily visible.

Unfortunately, I agree with your theory on the "something is moving that should not be moving". I haven't ruled out the noise coming from inside the tube. I do most of my own work, but I sometimes use Fast Freddies near Butler, PA. He thought the noise was coming from the center of the tube. My chassis sensor stopped working, but have ordered new stuff to make a few more. My plan is to figure out the bushing and get the new chassis sensor on the car to try to pinpoint the origin.