This was fun...
Trailing arm mount rotted out and detached itself from the car. This is a common "rot-out" area for W-bodies up north:

I re-attached the mount to the car with (2) 1" bolts, and a 1/4" steel plate on the interior of the car:

You can see the extent of the rot:

Here you can see how it's attached. I ended up swapping it so the bolts are welded directly to the mount, and the nuts are in the interior of the car:

Cut out the cancer, and re-boxed in the area:

Semi-finished result:

I have to take a picture of the interior plate, and finished product - I just forgot to at the time.