Mercman - Interesting truck! I wonder if that Tonner was sold as a chassis including the frame, drivetrain, front fenders and cowl with the driver’s compartment and bed being installed by an aftermarket supplier? The 1940 Ford Salesman Manual shows the availability of that configuration, but only for the 134” wheelbase and larger trucks. I can’t make out what the writing on the door says, but that might offer a clue as to its use.