The 'new' shakes most likely were always there. When you stiffened up all of your mounting, the shake became apparent, indicating another problem. For me, the shaking got bad after I replaced the rear mount. The mount itself was destroyed (See pictures in post #7
http://www.mercedesshop.=153575 ) This eventually to a new driveshaft. Ouch. Should have left the bad mount in place, as ignorance was smooth.