So i went on a road trip last weekend in my SDL and got a vibration, stopped at a mechanic who is a friend of a friend that often does work on older mercedes. He said it was my center support of the drive shaft, I made the trip home 8 hours, with the vibrating getting only slightly worse. However driving the car today for the first time since the weekend it shook violently at about 50mph. I have ordered the needed parts for the center support, as i was told the flex discs were not the culprit, and am planning on fixing it friday.

My question

Is it possible that such a violent shake can be caused by this, and will the car be okay on the fifteen mile drive to the garage in order to fix it?

Yes, it is possible that it is just the center support.
My 116 chassis 300SD had the same issue.

If you choose to drive it 15 miles, drive slow.

Prying the drive shift off the flex disc can be a real B. a new flex disc can be had for less than $40 and you get new bolts. If you have it apart I would replace them, i wish I had, because 2 years later my flex disc in the rear is vibrating. Be sure to replace the center support bearing as well.

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1959 Gravely LI, 1963 Gravely L8, 1973 Gravely C12
1982 380SL
1978 450 SEL 6.9 euro restoration at 63% and climbing
1987 300 D
2005 CDI European Delivery
2006 CDI Handed down to daughter
2007 GL CDI. Wifes