Originally Posted by BPlakGS300
I recently obtained a 06 GS300 Non AWD. There seems to be a vibration in the seat at 75-80 MPH after you let off the gas. Is that Drive shaft or Tire Balance problem?
The way I read/comprehend your post is your car is smooth until you let off the gas? As in at 75-80 cruising down the road its smooth yet the moment you take your foot off the gas the vibration begins?
If my questions above properly reflect your issue then wheel balance is probably not your source of the vibration. Rotation and balance is a quick and relative easy diagnostic step but if smooth to begin with you could just be wasting your money. More likely is transmission, driveshaft or axle shaft/CV joint issue.
I will cross my fingers its the tires yet if its the way you describe it, you probably have something more $$ to deal with..
Let us know