You kats aren't paying attention. I posted this link before. http://nitrogeezers.smugmug.com/photos/29989064-D.jpg
According to the book Ford Trucks Since 1905 by James A. Wagner the '38 -'47 Cabs are nearly the same except for minor trim details. The biggest changes were made to the '40 -'47 Cabs. The '38-'39 Cabs had opening windshields and wiper blades on the roof. In '40 the A-Pillar, Cowl, and Instrument Panel was changed to accomodate the fixed windshield and cowl mounted wipers. The upper beltline was relocated slightly as well. As you can see in my previous posted pic the '37 car front sheetmetal looks tits on that cab.
This pic and the other one I posted actually have '38 - '39 standard front sheet metal. http://nitrogeezers.smugmug.com/photos/29989067-D.jpg