Am I right in thinking T3 lamp units are a '60s thing, and if so, then they would all be 12V? I have a pair of Guide-style headlamps with T3s and it doesn't say anywhere on them if they're 12V or 6V. I have some other General electric sealed beams that have 6v stamped on the back. It might be irrelevant anyway, as I tried one of the T3s on a 6V battery and it lit, but filled up inside with white smoke! A sign of being FUBARed anyway, or because it needed more volts to 'burn' correctly?