ya i would say driveshaft, all manual MB driveshafts seem to
lose there balance , i have replaced them in every man. MB so far,
190e 16v, 190e, 300e all shimmed around 80mph for me
395.00 for a rebiuld one with your core , from d.l.s of Atlanta
404 361 9111, well wroth the money to have a smooth ride,

First check to see if the hugh counter balancer on the front of the drive shaft is falling off, if so just cut it off , Mercedes told me
that they removed the balancer from the driveshafts for heavy vibration, it weights like 20 lbs too , mine is off on my 16v
hope this helps

Dave
86 190e 16v
Iroc replica 911