I had the same identical thing happen to me recently, but mine was in my 72 Ranchero. I to thought it was my headlight switch, and went ahead and replaced it. It didn't help, the tail lights still didn't work, but the brake lights did, kept hearing clicking noises down around the switch, headlights flickered, etc. I started tracing wires under the dash and came across one that was really hot, just behind the glove box. followed it until it disappeared above the ashtray, but below the radio. I had to pull the instrument bezel off just so I could barely get to it. Everything was by feel with my arm stretched through the opening of the instrument panel. I moved what felt like a relay about a half inch, that was attached to the hot wire. After that I haven't had anymore problems with it. I think it was shorting out against the bottom of the radio chasis. I've been wanting to remove the radio and see exactly what it was that I moved, but I haven't had time to get after it lately, and haven't really driven it much since.
You might want to check if there is a connector or relay that might be shorting out, I'm no expert on trouble shooting the problem, but your problems are exactly what mine was doing. I guess I should get out there and see what the culprit was!
You might want to check if there is a connector or relay that might be shorting out, I'm no expert on trouble shooting the problem, but your problems are exactly what mine was doing. I guess I should get out there and see what the culprit was!