Good used headlight switch knob for any 1969-70 Mercury Cougar or Ford Mustang. To remove, reach behind the dash and locate the small, round spring loaded button on the top side of your headlight switch. Depress the button while firmly grasping the knob and move back and forth until it releases. To install, firmly and quickly press the knob inward (towards the dash) with the palm of your hand.
Ford part number C9ZZ-11661-A
Here is a helpful youtube video on how to go about removing a headlight switch from a Cougar or Mustang.