Thank you for alerting me to this problem and for the tip about the bolts. I checked my flex discs and the front one is needing to be replaced. Although I couldn't see any cracks in the rubber, the front one has rust showing around the steel inserts where the bolts go through. I've read on the MB forums that's one of the first signs (besides obvious cracks) that the flex disc is going bad. The rear one looks good. I think it might have been replaced at the MB dealership. I believe I saw something about it in the service records I got with the car.
I will be changing both, front and rear flex discs, as well as the transmission mount, while I have the car off the ground. All are relatively inexpensive and fairly easy to replace. I don't want to take a chance on the same thing happening to me that happened to the coupe from Virginia. If the front one goes out on a MB like mine it can take out the the transmission tail shaft housing, the transmission mount and crossmember, all the shifter linkage, warp the driveshaft, and beat the sheetmetal under the car all to hell. All of that over a part that costs less than $100 going bad.
As far as I can tell, the center support of the two piece driveshaft is in good condition. That's good because the exhaust system has to come off to get at it. Even though the exhaust doesn't have any rust on it, I don't like dealing with exhaust systems unless it's absolutely necessary. Seems like exhaust system bolts like to seize and break for no reason.