I just bought a 1969 chevelle convertible and the tail lights don't work, but everything else does. I tried changing the switch, but that did't help. The brake lights and all other lights are fine.

The Brown wire in the rear harness is the common power to both "tail" lights and the license plate light. Just check for power at the bulb socket and trace back till you find the problem. The wire originates at the headlight switch and there are connectors in the trunk between the front and rear loom.

Thanks for the help I'll give that a shot this weekend.