High speed vibration

Between 55mph and 65mph when accelerator pedal is depressed to gain speed, a vibration is felt in the steering wheel, accelerator pedal, seat of pants, and the shifting lever is seen visibly vibrating. I replaced motor and transaxle mounts, new tires, rotated tires, had front end completely checked out all to no avail. Any suggestions???

The balance was good on the tires?? Perhaps the new tires aren't very good...

Anything else changed before you noticed this vibration.

The balance was good on the tires?? Perhaps the new tires aren't very good...

Anything else changed before you noticed this vibration.///

Vibration was occurring before new Michilin tires were purchased. New tires were balanced, rebalanced, rotated etc. Wheels were checked for being out of round etc. Nothing else was changed out prior to noticing the vibration. I never have checked anything in the rear axle.
Could the rear possibly cause this type of problem??

Is there any bearing noise?? I would check you bearings.

That's an idea. I'll give that a try although I haven't heard any noise. Thanks.

loose clutch? worn? clutch bearing??? motor mount? rear motor/tranny mount?

Dont forget to check your steering column bearing, I'm dealing with the same issue on my GF's bunny