According to the book "Dodge Pickups history and restoration guide" the chrome grill with the straight horizontal grill bars makes it either a 40 or a 41. The horizontal grill bars first appeared in the 40 model year, and the chrome was not available after the end of the 1941 model production due to the war, and the chrome did not return after the war.

1 1/2 ton civilian trucks were available through 1942, and again in 1944 and 1945 in limited numbers and resumed full production in 1946. !947 truck production was stopped early because of and industry steel shortage. Supposedly no civilian trucks were available in 1943.

Of course, all of this is assuming the chrome on the grill is original to the truck, which could be a big assumption. Gene