I've been studying the heck out of the 1979 electrical schematics. When I first posted, I wasn't sure if the plug-in flasher units were voltage sensitive, the hazard and the turn signal units.
But now I have additional uncertainty about how the parking lights and the turn/hazard light system even works. I can't make sense of the circuits, the current flow. The schematic does not show the bulbs to be grounded, so where is the end of the circuit ?