The tail lights not working is a common problem on these trucks. This has especially been an issue after the bed has been repainted and the lights reinstalled as the lights do not get a good ground.
Some folks have soldered ground wires to the light bulb bucket inside the tail light assembly. Then, run that wire along with the other wires back to underneath the bed or to the frame rails somewhere.
I myself had issues with my '65 c10 step side with the tail lights. I had several things I found, shorted out bad wires in a rats nest of bad splicing, then I found a bad short, behind the fuse panel itself.
I also eventually had to replace my light switch as I started having strange gremlins and no amount of taking it apart and cleaning it seemed to help.
Good luck, glad to have you around.
If these answers don't help ya, go stop by the
Electrical Bay. Lots of people with a better understanding of electricity and switches hang out in there.
-W
