DieselHead: On the vibration/noise, first thing I'd check is the driveshaft support, that's what the description sounds like to me. The car has a 2 piece driveshaft, the bracket that holds up the "middle" joint has a rubber support, which can wear out and cause a noise like this. i don't connect the vacuum problem to the noise. The vacuum pump itself may be bad, which is common on high-mileage cars. Your cruise is electronic, not vacuum, at least if it's an MB factory cruise. i may be wrong on that, but I'm purty sure about it. Vacuum systems can be a problem. if the pump is bad, it can allow engine oil into the various vacuum operated systems and really compound the problems, the oil swells the rubber diaphrams and connecting hoses, causing further damage and failures. Is the engine still shutting off OK? Vacuum operates the shut-off, usually the first complaint is either the door lock system or the engine shut-off system. Yes, the transmission is about the same as a gasoline engine transmission. It has a vacuum modulator like a gas engine transmission, but uses an alternate scheme to get the vacuum "correct", so the transmission will work as though a gasoline engine is supplying the vacuum, instead of a vacuum pump on a Diesel engine. So a shorter version of this is "Yes, a vacuum problem can cause the harsh shifting".
Gilly