1984 Fox Body Mustang Wiring | CJ Pony Parts With affordable, easy to install harness replacement options, we make it easy to upgrade your 1984 Mustang wiring harnesses. Wiring Harness Gauge Feed 5.0 Liter 1984. Designed for all 1984 5.0 Liter Mustangs, this factory-reproduction gauge feed wiring harness is ready for you to install. 1984 Ford Mustang 5.0 Carbureted Wiring Harness This is an engine wiring harness for 1984 ONLY 5.0 carbureted Mustang. This is the harness that connects the main harness to the engine. It includes all of the connectors for the following: A/C, ignition coil, oil/temp sending units, connects distributor to ignition module, other misc pieces on motor.