1966 Ford Mustang Door Courtesy Light and Speaker Wire Harness. Now you can replace your cracked or deteriorated Door Courtesy Light and Speaker Wire Harness professionally with this perfect reproduction from Scott Drake. This 1966 Mustang Door Courtesy Light and Speaker Wire Harness is just like the original, with authentic styled grommets, plugs, connectors, and braided loom. This is a dire ct plug in for the under dash door light switch.