The Coupe, and particularly the more powerful S54 version, have a known issue with weakness of the rear subframe. The factory spotwelds fail as a result of stress from the too soft subframe bushings. This car showed no signs of the issue, but I felt compelled to change the subframe bushings anyway to the stiffer poly bushings. Same for the Differential carrier bushings. These changes are thought to prevent the issue or at least significantly reduce the probability of issues. Surprisingly, the subframe bushings were in fairly good shape and were probably done at some earlier point in time. However, the diff bushings were a mess on one side, and becoming a mess on the other. A good and timely replacement.