Try describing it with more details. Speed, gear, trottle, brake, engine
speed in different gears.

You can try three things:

1) Tighten the exhaust, replace rubber rings and remove any strain. Its
the main resonant body making feel small vibrations caused by other
sources. Look for a contact to the body (first pot is sometimes very
close to the heat shield).

2) Corrosion of the plane surface between rim and brake. Clean it with a
wire brush and let do the wheeel balancing with mounted tires.

3) The complete transmission drive has to be balanced if it has been
decomposed.

Check the motor and transmission mounts.

I have since jacked up the car and run the motor drivetrain in forth gear
and the vibration is definitely caused by the drive shaft. the exhaust pipes
vibrate dramaticly. I have added weights to the drive shaft and this has
changed the point at which the vibration peaks. Does anyone know what the
runout on the driveshaft is? I measure a 6 thousand runout on the shafts.
this car has only 60,000KLM
front and rear near the flex couplings