I have a round knob/switch on the left side of the center console on my 1970. It is down near the gas pedal and looks like a factory installed switch. Anyone have any ideas? I can not find anything about it in the manuals.
Thanks, Rick

Is it a vaccum or electrical switch?

I'm not sure if the 1970 models had it,but that's around about the location where my rear window de-fogger switch is.

It is an electrical swith and SAVETTE75 hit the nail on the head.
Thanks, Rick

I was thinking you were talking about the little knob at the bottom of the dash board,just below the steering column,that is the vacuum over-ride switch you pull it down to open the headlights with out turning them on with the light switch

thats right it is the over ride switch for the head lights so u can change the bulb or keep it open if the boot goes bad.