Hi all, thanks for the feedback!
The U-bolts were the 1st thing I checked as well. They’re tight. Frozen is more apropos. But there’s no play/movement. I thought he might have removed a leaf and didn’t tighten things back up, but I wasn’t able to get any movement from around the U-bolts or the springs themselves. Also, the rear end is not moving within the bolts (if that makes any sense). The top of the “U” is very much in contact with the rear end and moves when the rear end moves.
The spring perches are bolted, not welded to the frame.
Here is a quick video I just shot…