The clutch driven plate damper is defective.

1. Inspect the clutch driven plate.
2. Replace the clutch driven plate, if necessary.

Refer to Clutch Pressure Plate and Clutch Driven Plate .

The engine idle quality (engine firing pulses) is being transmitted through the propeller shaft to the transmission.

1. Inspect the engine idle quality (engine firing pulses).
2. Repair the driveability concern as necessary.

(This may be a normal condition.)