I have read a lot of previous posts about seat-of-the-pants vibration - without seeing a whole lot of resolution.

From 45-65 mph I have a vibration. I can see the passenger seat moving, I can feel it in the seat of my pants. There is no shimmy in the wheel. At 85 mph the car is smooth as silk. Applying the brakes does not make a difference.

The following has been done.

1. Drive shaft replaced w/new center bearing
2. New trans mounts
3. Balanced rear tires then swapped out rear tires - no change
4. Rebuilt both rear calipers - driver side was sticky.
5. Ran car on hoist - no obvious shakes.

I have no noises or other problems. Cars drives great. I just have this wicked vibration. Any ideas on what else to pursue?

Derek.-