I recently got a 65 Buick skylark and it has a accessory knob....it turns, left is on and right is off. I just got it so I haven't really gone through it but if I maybe had a list of what it could be then that would be helpful...thanks guys
Rear Window Defogger. It should be labeled 'High / Low' on the bezel. If the bezel says 'Up / Down', then check to see if you have a convertible top