Thanks GWest. You got me thinking & I went to check the other "tiller / reverse ready" tractor. It has all five holes drilled, but it is also a larger tractor. It has standard lug bolts installed in all the holes. No help there. Went to check my other model 20. It only has 3 holes drilled. Didn't pull the hubs to see if they frame the part number or not.
Today I skipped working on the engine. I realized I still wanted to repaint the gear case assembly to cover the chipped paint. I slung it from the rafters, scuffed it with a green Brillo, washed it with Methyl Alcohol, dried it with a lint cloth, then shot green & clear coat. It will need a week or more to cure, so that will give me time to work on the engine & remaining rim.
Then I went to haul wood with the Allis.