Delco Radio Harness | eBay original gm delco radio wire harness. gm delco radio connector pigtail. use to re-install original oem delco radio in your vehicle. all wires all color coded, just match the wire color to your wiring. nos gm radio adapter harness 78 to 77 camaro caprice firebird cutlass 16003170. How to: Delco Radio Wiring | It Still Works Older (Up to '89 to '90) Delco Radio Wiring. Locate three plastic plugs fanned out of a single harness bundle. Plug colors are blue, white and black. Each plug has four pin positions and may have four corresponding wires. All plugs are almost square, and have alignment ridges that guide insertion to specific slots at the rear of GM radios.