I am getting a vibration above 70 mph from the rear drive train, which particularly manifests itself when accelerating above 60 mph. I know that it is impossible to definitively diagnose something like this from just describing it. But, I am wondering if anyone has had this symptom before, and if so what was the culprit? I am pretty sure it is not tire balance as it is much too fast a vibration to be either balance or an out-of-round tire. Rather, it has the feel of a worn U-joint, slip spline, out-of-balance drive shaft or whatever is there between the motor and the rear wheels. Does anyone have any advice on what to look for? Is this something I need to take to a Tesla SC, or could a shop that does suspension work diagnose and repair whatever is the issue? Any advice or observations are greatly appreciated. Thanks!