Here are my 338s - 3AA 20x8.5" all around
My suspension is (i believe) a 77 C-10 setup. Still had to grind on the front rotor.
The rear looks like it would have enough clearance without spacers, but I don't like the way they set inboard of the fronts, so I just ordered 1" spacers. I did the same thing on the TTIIs I had on my 72 GMC.