Nice! Did you leave the reflectors inside and connected? (just sans lamps?) Or did you remove the extra reflectors? Looks like you could even leave the lenses in place since the blanks appear to bolt on outside the fixture where the visors go?

I left the reflectors still intact inside; however, I removed the lenses for possibly a future project. In any case, what was common is that the lenses, reflectors, and lamps were untouched if blank doors were installed.

You are right. You install the blank door in the exact spot a visor was, and vice versa.

Oh wow so the lamos would actually still be running with the blanks in place? I guess back then, energy usage wasn't a huge deal like it is today.

I guess so, I would imagine later on they would take out the lamps to save energy. I've seen CGE signals here with a similar blank door. Basically a round piece of sheet aluminium you install in place of the visor that covers up the lens. I know Eagle had blank doors that replaced the entire door assembly though.