1989 Toyota Supra OE Wiring Harnesses & Stereo Adapters Toyota Supra 1989, Aftermarket Radio Wiring Harness by Beat-Sonic®, with OEM Plug. Includes 10-Pin and 6-Pin Stereo Connectors. Stereo wiring harness for vehicles without factory amplifier systems. 1989 Toyota Supra Hitch Wiring | Harnesses, Adapters Toyota Supra 1989, Professional™ Inline to Trailer Wiring Harness Connector by ACDelco®. Designed utilizing the latest technology, this product by ACDelco features premium quality and will perform better than advertised.