It's for fresh air
You should be able to push and pull that knob. It allows for fresh air to come in through the cowl vent. If you look up underneath the dash that knob should have a rod attached to an arm that opens and closes the vent door. If I recall correctly, you pull it for fresh air...
I used a LED license plate light. I bought mine from Super Bright LEDs – LED Lights, Bulbs, and Accessories. This is what I bought, works pretty good. I mounted mine to the windshield frame above the rearview mirror so that I could still have a dome light when my top is off.
LPC License...
My money pit........
Here is mine. This is my first attempt at a photo attachment. It's a 72, with 4" lift, Centerline wheels (don't like them, don't seem like they fit the look) 33" Maxxis tires. I have aluminum half doors on now, but don't have that picture on my computer. Just installed...
You might try this place OEM-Type Bullet & Spade Electrical Connectors for 1960's to 1980's Japanese Vehicles... Bridgestone, Datsun, Hodaka, Honda, Kawasaki, Landcruiser, Suzuki, Tohatsu, VW, & Yamaha
From what I think you are wanting it shows connectors you are describing.