You can put 19.5" tubless wheels on it off a late model P30 chassis. The lug pattern is 10 x 7.25". The front axle only uses 5 of the 10 studs, the rear uses all 10.
I would like to have a couple of his old wheels. Those should be 3-piece wheels. They are perfectly safe if they're in good shape. I have 6 that I restored and am using on my '50 1.5 ton, would like to have a spare or two.
