Just wanted to thank everyone who posted to this thread - I was having trouble with vibrations after changing my the front flex disc on my '80 300CD. I figured the next step would be to replace the center support bearing. Read this thread, though, and thought I'd give it a try. I loosened the tranny mount bolts, the drive shaft slip nut, and the center support bearing carrier bolts; rolled the car back and forth a few times in the driveway; jacked up the car just a tiny, tiny bit -- barely enough to get my head under there to see what I was doing; tightened it all back up; and what do you know -- vibrations are gone! Took less than half an hour and I am so very pleased that I don't have to replace the center carrier bearing. and it was a no-cost fix!

Well almost no-cost. I did invest in a 41mm crow's foot -- had been using channel locks and a big crescent wrench before. The crow's foot makes easy work of the slip nut; a big plus is there is no need to move the exhaust out of the way.