Seems like I saw some where chevy wasn't making 2 tons till a little later. If so with the helpers it could be considered a heavy duty 1.5 ton. I do know for 1938 they list 157 inch wheel base as being available as either 1.5 w/o helper springs or heavy duty with helper springs. Since it's a 41 the vin plate should be on the cowl in the engine compartment on the passenger side. Any possibility it's been covered by some bolt on fire accessories such as electrical boxes and such to run sirens lights etc?