odd speed related vibration. Tires or driveline?
 

I was driving my friends 560SEL the other night. The car operates perfect but I know he needs to replace a few bushings up front, maybe ball joints too. Now when travelling over 60 MPH, there is a noise heard in the front of the car almost as if something is shaking or loose thats why I suspect a bad ball joint? A shuddering noise is what best describes it. Now for the vibration, as you go faster over 60MPH, the vibration gets more noticable and can be felt in the cabin. Could this be the tires out of balance or something more? His suspension seems good but getting tired. SLS in the rear is in operating order. What could be the prob? Tires have been roated but vibraton/faint noise still present. Last balance was about 4 years ago when he got the tires new. Tires are the expensive Michelin MXV4 plus tires, lots of tread left. The car has 60k miles year 1987

As for the vibration, safely get under the car and grab hold of the drive shaft and push it up and down, first by the transmission tail drive shaft flange, if you feel movement the transmisison output shaft bearing is defective, do the same test on the drive shaft were it mounts to the center support and to the rear differential.