Also, the some of the lights that are currently on may dimly light right after the brush installation, this is due to the non broken in brushes, with some time it should go away.
Alternator brushes. I've heard of 60's doing funky things like that when the brushes are on their way out. Its a cheap part, easy to do, and if your alternator is original, it wouldn't hurt anyway. This is one of those things where you can go ahead and throw $15 at it and see if it fixes. My...