Used Engine Wiring Harnesses for the Mazda RX-7 Used Engine Wiring Harnesses for the Mazda RX-7 for Sale. Get a great deal! Our used auto parts locator service will help you get a great deal on the used Mazda RX-7 engine wiring harnesses you need for your car, truck, SUV or van. APEXi Power FC Adapter Kit (89-91 RX-7) - Banzai Racing Harness Adapter will fit all S5 ('89 - '91) Mazda RX-7 Turbo II's. This Harness Adapter Kit will allow you to install the FD3s APEXi Power FC (NOT included in kit) into your Series 5 FC3s without modifying your Engine or Dash Harnesses at the ECU.