you made me curious about frost shields, I was thinking about the stick on plastic no-fog things people used to put inside their windows.
I found this 1956 GMC accessory catalog
https://www.xr793.com/wp-content/upl...ry-Catalog.pdf
But the 'visor listed' looks like this
which is pretty cool, I have never seen one fitted to the cab like that.
looking for old fulton ads, this is a frost shield:
and this is a sun shield
Do you have a picture of a 1950s frost shield ad?