I had a major clunk in my runner as well from the rearend. I tried to track it down for days with help from others on here. Finally, I went back over every bolt and nut underneath. I was able to get about 1 full turn on the nuts on my panhard bar top mount. After I did that, noise was completely gone. Then a week or so later, I installed Toytec Panhard bracket. Clunk was back. what I had to do then was where the end of the bar goes into the panhard bracket I bought, there was about 1/4" gap that allowed the upper end of the panhard bar to move forward or backward on the bolt causing my clunk. I took a couple washers and placed them between that bracket and panhard bar, tightened back down, no clunk. But that was my issue, yours may be totally different.