Here are some other ideas for you. Portrayal Press specializing in military vehicle manuals, GMC, Chevrolet others.
www.portrayal.com
Vehicles of Victory - Tom Dienst
www.vehiclesofvictory.com
www.militaryvehiclesmagazine.com
They have a communications page where you can post questions. The editor is [email protected]
I also went through my 1942 Salesman Data Book, they do not appear as an index item nor is there mention of any.
http://www.flickr.com/photos/advance-design_parts_co/8374820410/in/set-72157631872034068

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