Appreciate you adding to the information Bill. It seems this was used on the 102 Long Bed models then, including Andy's '46. I also found in my new to me books both a 1939-40 and 1939-41 GMC Book of Parts. When I get a chance I will look and see if they have anything that relates to that weird "1940 AC" mention in your book.

~ Dan
1951 Chevy 3 window 3100
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"My Grandpa Carl's Truck and How it Became Mine"
1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver)
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