Tim,

First they could be NOS Ark-Les switches, pretty common switch. I have never owned a fog switch but have made some observations about how the various switches are boxed. Switches that come with installation kits are usually like these pictured, plain box with a GM part number.
https://www.flickr.com/photos/advance-design_parts_co/8129441328/in/set-72157631868452754
https://www.flickr.com/photos/advance-design_parts_co/15694490319/in/set-72157631868452754
Ark-Les single switches are either in a box like you show in your first post or in a plain box with a 3-digit code.
https://www.flickr.com/photos/advance-design_parts_co/15265362743/in/set-72157631868452754
I have personally never seen an Ark-Les switch in a GM box. Could an Ark-Les switch be put in a box and advertised, sure. Another point Ark-Les or Delco or Cole-Hersee heater switches in NOS condition run about $50-$70 for $265 I can only hope the contacts are gold plated. Fog light switches on the other hand routinely sell in that $250 range. I have never owned one but have noticed they are a much rarer item then heater switches.

1950 Chevrolet 3/4-Ton 3600
More pictures on Flickr