The '33/'34 cab is slightly larger (longer and wider) than the '32;and the firewall was configured differently to provide more legroom; and the back of the cab has additional ribbing that the '32 does not. The front and rear fenders are completely different. And the bed on the '33/'34 is longer and wider than what's found on the '32.
The frames are not the same between the '32 and the '33/'34. The '33/'34 has a kickup in the front that the '32 does not have. And, of course, the grilleshells are different.
As I understand it, you can swap out the '33/'34 cab for the '32; but everything else will need to be '32.
The '33/'34 truck frame is the same as the car. Why not just start with the '33/'34 car or truck frame? The front fenders from the big trucks are slightly wider than the pickup truck fenders; however, they don't have the spare tire pocket, and many guys like that look.
I think I'd look around for the '33/'34 pickup truck or car frrame and use that as my base. Easier in the longrun. But it would turn on whether I had the rear pickup truck fenders. They are almost impossible to find anymore in steel (readily available in fiberglass). The only advantage that I see of going the '32 route is that the Brookville repops are available. Otherwise, I dunno....I'd stick with the '33/'34.