Features: Fitment: Locks flywheel in place when removing harmonic balancer on 6.6L Duramax engines with Allison automatic transmissions. Function: Saves time by locking the flywheel at the transmission instead of having to remove the starter for water pump replacement. Duramax 2500 / 3500 Pickups (Toothed pieces only): Removes metal spring-loaded inspection plate on the bottom of the transmission. Tool should slide into opening toward engine with the top of the tool engaging the teeth of the flywheel. .