Have you checked your flex discs lately? As opposed to domestic vehicles with U-joints, Mercedes have a flex disc in the front connecting the transmission to the driveshaft and, in the rear, another flex disc connecting the driveshaft to the differential. These discs are made of rubber. If there are any cracks in either one it should be replaced right away. A broken flex disc could cause very serious damage to the transmission and driveshaft, among other important parts. Every time you are in for an oil change or maintenance service, the flex discs are one of the many things we carefully inspect to make sure your car is safe and reliable.