Dan,
Which tail lights do you have ? The round ones or the single lens rectangle .
The only reason I ask is because I had similar issues with the rectangle ones. They use the Prince of Darkness bulb sockets and they SUCK ! I happen to see a superformance rear taillight assembly and knew that was the best way. Instead of buying theirs I just fabbed my own. I wanted better bulb sockets rather than those I had so I went to the U pick and found some really cool metal ones out of a 70's car. My problem went away. I know too you better have super good grounds with a glass car.
Don't mean to waste your time. I hope you find your issues and get back on the road.
Hersh