1949 Chevy 3600

Hello all, I need some help smile

I'm trouble shooting the LR tail light. I have running lights in the back but no brake or turn signal.

How do the dual element 6V bulbs work? Is there a resistor in the tail light?

Here's what I know:

-Flashers in the front work
-Flasher on the RR works
-RR brake light works
-Both bulbs work normally in the RR housing
-Both tail lights work
-The LR brake light and turn signal do not work

The wiring to the light must be okay because the tail light works.

Any ideas?

Thanks Y'all
J&K