Hello Ernie,
I can't follow with that:
there were some slight changes to the December 1940 build card compared to the earlier 1940 build cards.
I tried to compare but can't make out changes there? Did you mean 1942 instead of 1940?
Before 1942 they stamp "US WAR DEPT" and later on the "US WAR DEPT" was already printed on the card.
In February and March 1943 they used again Build Cards without "US WAR DEPT" printing. Maybe because of shortage in blank cards and great quantity of produced Trucks?
Interesting on the 1940s Trucks are the different ignition key numbers. Later on all show H700. Do the early Trucks realy have different keys?
Greetings
Sylvia