Mil-spec Tucked 13B Harness (FD3S/Rx7) This wire harness is made specific for a RX7 FD3 Chassis, not intended to be used for a 13b standalone engine harness. For "Right hand drive" customers, the ECU type will be for the earlier model (Our harness does not support the Austrailian 16-bit ECU's from 96-98) rx7 engine harness | eBay Find great deals on eBay for rx7 engine harness. Shop with confidence. Skip to main content. eBay Logo: Engine Wiring Harness Mazda 93-95 RX-7 5 speed FD3S #n3a1-18-05zg See more like this. 1983 Mazda RX-7 12A Engine Wiring Harness See more like this.