From what I've seen one these trucks, the 20" wheels for the big trucks are the same (?) from about 1930 to 1940, and have a shallower dish than the '41-'5? wheels.
One thing you'll want to check out on your chassis is whether you'll have clearance to the frame rail (or whatever body is going behind the cab) when you turn those rear wheel "in".
We have a '36 low-cab that has duals and I was pondering making a 1.5 ton "Express" (pick-up), but there's only about 36" between the sidewalls of the 6.00x20 tires, which doesn't make for a very wide pick-up box.
The sales illustrations always show the 1.5 ton Express models with single 20" rear wheels, mounted dish-in, llike the fronts....don't know if they had a wider rear axle....
Frank McMullen
