Ford Performance Mustang Multiport EFI Wiring Harness M Installing the iconic 5 V8 pushrod engine in your very own custom car or Foxbody Mustang just became a lot easier with a genuine Ford Racing Multiport EFI Wiring Harness. Complete Harness. The Ford Racing Multiport EFI Wiring Harness consists of a single harness with integral connections for injectors and O2 sensors.3.8/5(5)Brand: Ford Performance 1989 mustang wiring harness | eBay Find great deals on eBay for 1989 mustang wiring harness. Shop with confidence. Skip to main content. eBay Logo: Shop by category. Shop by category. Ford 5.0 EFI universal wiring harness 1989-1993 (Fits: 1989 Mustang) Brand New. $550. Buy It Now. Free Shipping. 139 Watching. Watch.