cletis,
I would have to agree with you, if a farmer needed a truck (big or small) they took whatever the dealer had or what they could get in a reasonable time. I also agree that the five window was far from being rare. But then again I have seen many 2 tons (five windows) with the stainless exterior trim on the doors and windshield. But here again, all cabs were the same and maybe that was the way it came about at the factory, if they needed orders for 2 tons and needed cabs right then and the five windows were the only thing available at that certain time, then that is what they got.