I am running the OBD2 distributor with my OBD1 setup, so don't need it. If you convert the engine harness to OBD1, you would need it, but if you are just using a conversion harness, all functionality of the OBD2 stuff should work (assuming you are using a P72 ECU). The only issue with the conversion is the EVAP purge solenoid which the OBD1 ecu doesn't support, so just unplug it.