Differential cover.
 

I’m being a little cautious perhaps, but I have the differential completely loose, but the rear cover mount is stuck to the subframe. I removed the rear mount from the rear floor and removed the rear mount. Am I missing something? 87 560SL
Bdbenz

The diff cover has sealant and you must gently pry it off to break the bond. Keep a drip pan handy this is a messy job.

The job will go a bit more easily if the rectangular rear mount is left bolted to the rear floor, and to the sub-frame (axle carrier).
Remove the single vertical bolt that connects the diff cover to the sub-frame, and the two vertical bolts at the front of the diff.
The rubber isolaters may stick to the sub-frame; judicious prying required.

Thank you. I was able to get the long bolt from the cover out and dropped the diff. Went well after I got everything unbolted.