1978 el camino wiring harness | eBay Find great deals on eBay for 1978 el camino wiring harness. Shop with confidence. Skip to main content. eBay Logo: Shop by category. Shop by category. Enter your search keyword OEM 1978-1987 El Camino & GMC Caballero License plate light wiring harness See more like this. 1978 Chevy El Camino OE Wiring Harnesses & Stereo Adapters Chevy El Camino 1978, Aftermarket Radio Wiring Harness by Scosche®, with OEM Plug, Power/Speaker. Up yourself and your tunes over the factory installation with top-of-the-line audio products from Scosche.