Ordered left and right chrome caps. Doorman # 959-0018 and 19. Took the glass out again and unsnapped the cap clips with a flat screwdriver. They break easy.
Looking at the back of the covers, it's clear that the exact same tool molded these. Everything is the same from the parting lines and ejector pins to the gates and sprue. The part number is off by one, probably for the chrome vs. black. I would bet that doorman or their source makes the whole mirror.
I haven't decided if I'm going to take them back off and paint to match yet.