Vent windows appeared in 1951.

Pull down door handles were replaced by push buttons in 1952.

If the doors are original to the vehicle, that makes it a 1951 at the oldest. We know the doors are no older than 1951.

Does the cab have a driver side cowl vent? 1950 was the last year for that feature.

1950 Chevrolet 3100 (Ol' Roy)

1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)