Classic/Antique Car Repair: lights on a 50 Dodge Coronet, radio clock, dodge coronet

Question
I am getting desperate to solve a lights issue with this car I inherited.
I will start with what works-headlights, parking lights,dash, dome, radio, clock, license, and right turn signal(sort of), and left turn signal(sort of).
What does not work-tail lights, brake lights,left rear turn signal only works with headlights on and is very dim, right rear turn signal only works with headlights on.
I have the wiring diagram and have tried to trace every lighting wire on the car. It all looks good except some wearing on a few wires that I have since taped. When I switched the right rear wiring to the left side, that lit up like the right rear has. Still only when headlights are on but no longer dim.
I am still hopeful.

Thanks

Answer
It sure sounds like the tail lights are not properly grounded. This could be rust accumulation under the mounting of the tail lights to the body or the sockets not grounding in the tail light themselves. Try the grounds and get back to me and we will go to the next step.