I'd say this truck is a '47 or '48, assuming it is all original.
The presence of the driver side cowl vent and the lack of door vent windows suggests '50 or earlier. The hood side emblem, with no series number under the "CHEVROLET", suggests '47 or '48. This emblem should say "Loadmaster" also (can't tell in pics).
There's another recent post regarding the long arms for the mirrors on the AD big trucks.
