I have a very noticeable vibration in my '87 560sl that starts at 45mph and gradually gets worse and peaks at around 65mph. I've had the wheels dynamically balanced 2x and had the front end checked and aligned. It also has new tires. My shop went back and looked at the wheels (original 15") again and found one that was slightly bent. They replaced it, but car still vibrates.

I've eliminated the drive train as the cause (engine & transmission) since car still vibrates at 65mph even if I use different gearing. The only thing left, I'm told, is the rear half shafts or the drive shaft. Half shafts have 75k miles on them and boots are intact, but dry rotted. No signs of leaking oil yet! How likely is it that the half shafts could be causing the vibration???

Thanks,

Steve