Ive got a tricky issue to try and explain..dont know if anyone else can relate with this or have the same effect:

 

(Jap spec autobox, overdrive on)

 

Drive down the road (normal driving, not flooring etc), car drives fine...

 

Foot down, get some speed, foot up, in last gear, foot off, car seems to vibrate some, but then sometimes getting up to that speed its ok? Its not consistent, and doesnt happen lower down the speed range, prob around 50 ish...

 

as i say, difficult to describe so i know its a long shot but...

Prop centre support bearing failed, sounds like the actual rubber " donut" has broken free of the suport housing, common fault is more age related than mileage.

 

Jeff TT