When I check my Haynes manual it says instrument panels panel wiring has 13 bulbs but, there are 14 places for bulbs. It appears that the top upper right window is reserved for "optional temperature" gauge, or maybe an additional "idiot" light. My wiring harness has an additional green with black wire that is non-terminated, but also available along with two terminal ends for power ( red with white stripes). I have an extra available bulb.Does any one install it in the right window or do you leave it unconnected ? Additionally in George's TechTips 700, image 700, right side on page 97 it shows the stock face plate with the oil light on the right side and the generator light on the left side with black center button. Mine has silver center button with same configuration as right image, (not left image) but my oil lamp is on the left side and generator light on the right side.
Back side:Click to view attachment
Flashlight thru brake portal window:Click to view attachment
Flashlight thru "optional temperature "gauge" window:
Click to view attachment

There should be a transparent red cover over that brake light--the whole upper section. Only one of those two sockets gets a light, leave the other one empty. Either that, or splice new wires into the brake warning light circuit so you can put two bulbs in--but I think that would be too bright.

The green/black wire is for the oil temp gauge sender. The red/white wire is power for the oil temp gauge. You don't have the temp gauge, so those should be taped out of the way. (And don't let the red/white touch ground.)

The silver center is correct for 70-73 cars. Looks like your gauge is the right type for a 70-71 car.

My advice: Ignore the extra place for a bulb. Put the thing together and move on to the next thing.

--DD

Yes. At night that guage is almost impossible to see. Look up Toms thread on instrument lighting. It's the only way to have that guage light up. IMHO