The late '31 Budd cab is unique and different from what was used in the V8 era.
The Model A Steel Tops had a seam that runs in line with the rear door jamb up over the top from one side to the other.
(the steel top is just placed on top of the cab in this picture)
(a shot of the roof and specifically the integral visor)
(The stamped steel top bows, specific to the Model A top. These were given to me by John Charlton in England)
(Overhead shot, you can see the molding that covers the seam between the top and the rear wall of the cab. Please, forgive the whitewalls, I was young and didn't know any better)
The V8 era tops curves down in the back and the seam is a few inches below the roof line on the back wall of the cab...which you can see in this picture.
I'll try to take some pictures tomorrow in the daylight to show some of the other features.
-Tim