This might be off topic but related to the license lamp hardware and details.
I have two lamps, both appear to be original 67 lamps, but no date stamping noticed on either.
I did notice a black daub near one rivet on the one removed from my project car but keep in mind that doesn't mean to say it is the original one to my car because I know of at least 3 times that I had that bumper off the car when I was close to several other vehicles for parts donors so no way to be sure. I was hoping to find a date stamp to prove or disprove it being the original.
Anyways, about the black daub. I see another daub at the bulb socket.
The other lamp looks like a daub of black, (perhaps sealant) to temporarily glue the gasket in place?
I also observed two different clips for the mounting screws, the clips that slide onto the lamps. Perhaps different assembly plants or time periods.