#20103- 12 circuit
http://www.painlessperformance.com/webcatalog/largeview.php?SearchField=20103#20104- 18 circuit
http://www.painlessperformance.com/webcatalog/largeview.php?SearchField=20104these are our universal muscles car harnesses, the 18 circuit is designed for those with power locks/power windows. With what you described & not knowing if you have power locks/windows, the 12 circuit would certainly allow you to re-wire your el camino as well as add in the aftermarket parts you have, or are thinking about.