The term 'Drive Train Part' refers to a component of a vehicle's drivetrain, which is the system that transmits power from the engine to the wheels. The crossword solution for this term is 'GEAR, ' which is a type of wheel with teeth that meshes with another toothed wheel to transmit rotational force. Gears are used in many types of drivetrains, including manual transmissions, automatic transmissions, and differentials.