Hey man,
My 61 had a similar problem. I had not rt blinker and no lt brake light. I took the tailight assembly apart, I put new grounding screws for the tailights, I sanded all the contact points shiney, and i fixed some bad wiring under the bed. Anyway, what made the difference was the clean contact points, after that it all worked like a charm, I didn't even have to add any ground wires. Good luck buddy.
