2012 SVTPP with a heavy dose of 2013 components
I have had clunks, but their resolutions were never the upper per se. I think I had a shock that backed off a couple times and I did have some driveline noise that quieted down after adjusting the driveshaft angle. Changing the bushing on the top of the rear axle helped with that too. Here's the deal with the UCA. Lots of guys use the factory bracket, but the hole in the factory bracket is oversized. If it's not torqued to spec it has a lot of room to move around. That doesn't appear to be your issue for the bracket, but you might want to check how bolt to see if it's tight. I've always tightened mine on the ground before installing because it's almost impossible to do it on the car, especially if you're using a torque wrench. The bushing on the other end of the UCA is pretty flimsy. Energy makes a poly bushing to replace it.