1979 K20 pitman arm rubbing my 315/75/r16 - is this normal?

[LuckyLightning]

I'm usually a 1960-1966 truck guy, so this is my first square body. Also my first 4x4 with straight axle.

I have some Nitto Grappler 315/75/r16 tires with stock 2000-2003 HD aluminum wheels on my truck and every time I crank my steering wheel all the way to the right, my front driver tire rubs the pitman arm pretty good. It leaves a mark on my tire and is tearing up my output shaft seal on the steering box. So naturally, I try not to do this right now.

I bought the truck a few months ago the way you see it now. I don't think there's a lift installed, but who knows (there's no block at least).

My question is: is this normal? I see other drivers with this size tires (usually with a 2.5"-4" lift too) and no one has any issues with their pitman arm. I doubt it's a back spacing issue, since no one else with these wheels seems to complain about this issue, but again you never know.

Is it possible to remove the pitman arm and re-install it "re-keyed" so it's turned away a little from the tire so it doesn't touch anymore?

I have 4.56 gears so I really don't want to go to a smaller tire. Would love to know if there's something about the pitman arm that can be changed to fix this... or maybe I just need to go back to the old steelies...