I have been getting a mild vibration around 50mph.I balanced the tires and no change The driveshaft rubber support looks brandnew.Rims did not look bent or warped.Anything else I can check.The faster I go the smoother it rides but slower speeds seem to cause the slight vib. any ideas????

 

might try moving the rears to the front to make sure there isn't a tire issue. is there any play in your steering linkages. then try a steering damper. the mini shock on the linkage. cost is cheap online at autohausaz.com. still could be in the drive propeller shaft assembly. have the couplers been replaced, if so, properly?

 

Have you checked to see if your engine mounts are broken? I have a 94 SL and have replaced mine twice. They seemed to have caused this problem.

 

I had the same Problem on my car I balanced all four tires,even swapped tires from front to rear it still did the same thing check the drive shaft and all the joint they were good and whole car shakes at 70km/h so got a new drive shaft put it in and now car drives straight as an arrow I guess My old shaft was of balance a bit and that what was the problem

 

Where do you feel this vibration? Steering wheel or seat?