PDPlot, There are so many things that can go bump in the night on those rears, you may find more than one thing that is giving you grief.
I do agree the mounts are a big issue for cracking on the right side at the top, there is just enough space you can get a hand between the body and the frame to feel in there or take the wheel off and use a mirror and a flash light, the bolt goes through the frame and is welded all around, it will be easy to spot a problem.
Wayne