I don't beg to differ but
you can buy as i have shown a dual filament socket to use as a brake/tail or blinker tail or what ever combo you wish. tou can also just buy an LED set-up w/ all # on one unit and they work very well.
you should ALWAYS wire a dual filament incandesent bulb so the commonly used feature/light, in this case the tail light is on the lesser brightness filament. this way when you DO turn on a blinker or brake?? depending on how you choose to wire it, the second brighter filament shows blinking or STOP brighter & better.
That IS what you want isn't it.
I wired my dual filament front parking lamps this way and they work a

treat.
I have a triple LED set up inside my original rear housing and every one of them works just fine.
http://s67.photobucket.com/albums/h298/1951otter/?action=view¤t=587685-R1-032-14A.jpghttp://s67.photobucket.com/albums/h298/1951otter/?action=view¤t=587685-R1-030-13A.jpghttp://s67.photobucket.com/albums/h298/1951otter/?action=view¤t=587685-R1-036-16A.jpghttp://s67.photobucket.com/albums/h298/1951otter/?action=view¤t=4472530-R1-019-8.jpgor add a separate blinker elsewhere..............
