......and the turn signal switch "routes" the flash to the appropriate bulbs appropriate filament, controls the brake signal and activates the flasher. On a dual filament bulb, as Jorb says, one filament is only for running lights and is connected to the headlight switch. The other filament is for both stop and flash. On a turn, the Turn Signal Switch turns off the brake light signal to allow that filament to flash. Otherwise it would not flash because it would be receiving steady voltage from the brake switch.
Jorb has you covered on the wiring. Good diagrams.
I have removed most of my info in favor of Jorb's detailed info.
You will need new rear light assemblies. Available
Here. These light assemblies will have sockets that accept dual filament bulbs and have two wires.
In the front, you could dedicate the single filament bulb for turn signal only and disconnect it from the headlight switch. If you want park or running lights, you will need the dual socket treatment up front. Also
available
