I just finished replacing some very tired rear subframe bushings on an '82 300td. The back end of the car was sagging slightly (half an inch) and the rear axle was clunky over potholes.

Raising each subframe arm with a jack, I saw significant movement of each arm before the body of the car began to rise. I also noticed that the center part of the bushing, which had seized to the mounting bolt, was stretching out from the part that is pressed into the subframe arm.

No amount of penetrating oil was going to budge the bolts from these bushings. On one of the bushings, I'd crank the bolt a quarter turn and the elasticity of the bushing would snap it back. The threads on the other bolt were also frozen to the chassis, but that's another issue.

After some intensive head-scratching, I dragged out some Bosch Roto-Zip Sabre-cut bits I had on hand. These are rotary tool bits that are made to cut through wood or drywall. I detatched the two small bolts on the spider covering and worked through it to carve through the rubber in the bushing. I turned the bushing bolt to rotate the spider, then carved some more, working around to all sides of the bushing. Eventually I cut the center of the bushing free so I could remove the big bolt.

With the spider, bolt and bushing hub on a bench, I soaked it with Kroil penetrating oil, heated it with a torch and pounded on the bolt with a 21/2-lb. masonry hammer to no avail. I eventually had to cut the bushing off the bolt with a cut-off tool so I could re-use the spider.

As for the diff mount, a bad one will produce enough negative rear wheel camber to produce wear on the inside edge of your tires.

HTH
Russ M