The Bosch 04038 Ignition Rotor pushes on to the distributor shaft inside the cap. The rotor spins around inside the cap where it contacts the center post which gets power from the coil and sends power to the individual spark plug posts on the cap.
Bosch ignition rotor for 2.0L AC Vanagon (California emissions) and 1.9L WBX, 80-85. Gasoline, not suitable for diesel.
Bosch part # 04038