Non-Trigger Ring Harmonic Dampers read crank shaft signals off of the back of the engine. E46 M52tu and M54 engines use the Non-Trigger Ring Kit (OBD2) which includes:

Damper

Pulley, standard

Mounting and installation hardware

Trigger Ring option for OBD1 systems, adds a trigger wheel to the Non-Trigger kit listed above. Trigger Ring Harmonic Dampers reads crank shaft signals off of the front of the engine.

THIS IS OBD1 SYSTEM

5 GROOVE ALUMINUM DRIVE PULLEY M50, M52, M52TU, M54, S50US/S52US. THIS PART IS EXTRA WITH NO CHARGE