I know GMC often used different axles, hubs and wheels than Chevrolet on larger trucks but I don't have any real knowledge of what, when and why.
The serial says its a '46 while you've called it a '40 and looking at the pictures I'd be inclined to call it a '40 too. However, I suspect GMC used the '40 sheetmetal and grill on some trucks as late as 1946 and possibly even 1947.
I'm guessing here based on what I know they did in other years with other series of trucks, but it would fit the GMC pattern.
So what about this truck is unique to a 1-ton versus unique to a GMC? I wish I had all the answers to that question...
