You won't find anything that old on a VIN decoder, as standardized VINs didn't come into use until much later.
If you're looking at the engine, I'm seeing that a DBM prefix indicates a 1946 engine built in Tonawanda and installed in a 1/2 ton truck.
The vehicle serial number plate is on the right side of the cowl under the hood on '46 trucks. Look there and see what it says. A 1 ton would have a DS prefix and a 1-1/2 ton would
have a prefix of PJ.
You can get a Vehicle Information kit that has that information from the GM Heritage Site
HERE
