This might be a silly question. Did you have your trunk coated when you had the car painted? If by chance you did, did you check to see where the wiring harness goes to the left side of the trunk fender weld? That is where you tail light wiring harness will plug into your center harness....did they put this plug back together? We were having problems with our brake lights on our '69 Bird which turned out to be our turn signal in the steering column. I tested with a light tester. I took a tail light socket out of the tail light and removed the bulb. Then I grounded the tester and used the tester in the socket to see if they had power and the brake light lit up without the socked being plugged into the tail light. As you notice the sockets are plastic that come with the car and I was able to get them to light up without them being plugged in. I believe that the grounding is internal in the wiring system because we had mechanics try to fix our brake light problem with a grounding system and we weren't getting any power to the lights because the light tester wouldn't light up. It turned out to be a power problem.