I'm no expert, but it looks like a 45-46 to me.
Here's lots of pics of the 41-46 trucks
https://www.flickr.com/groups/2154916@N25/
There is some talk on the web about trucks made during the war, which would be few, and that they would not have any chrome on them.
Looks like you only have the cab, so that won't help. One guy suggested to look at the glass numbers has they have production dates, but that is not included from what I see.
Best guess is that it would be a "post-war" vintage. But right after from the shape and all.