Why is this picture called "The Dodge?" Am I missing something?
As to the guage question, most US spec 1200s (at least every one I have) didn't come with a tach and that blanking plate was used to fill the hole. The thing on the top of the dash is a "Fasten Seat Belts" light. I took the lens out and repainted mine to say "Get Out." I was going to wire it to a switch so I could throw people out of the car without having to say anything!

I've looked in scores of US coupes and sedans, and not one had a factory tacho.

I believe mine had a factory tach. It had the same look, ie. number font, type of needle, color, as the factory speedo. I'll see if I can find some pics of the dash.