I have the same KW sign. It's supposed to be a replica of a dealer sign from, I believe, the 1950s. I bought it from ATHS a little over 20 years ago. I collect what I can, and have saved a few things from my career.
My truck was built from the latest reissue of the Astro kit, but the mirrors came from an original issue Chevy Titan kit. I believe only the original Astro/Titan kits had these mirrors.
Nice Titan, Ken. I love the background, too.
I think only the early Astros had these, as they don't seem to appear on later models. They were very small and I would imagine not as easy to use for seeing to the rear. I used these because they are rare. I also prefer the larger mirrors.