disc axle tool

I bought an Allis 10 ft transport disc (what I'd call a "wheel disc"} over the weekend for a salvage project. Did they make a specific tool to hold the plate on the inside end of the axles when tightening or loosening the nut on the outside end? I've used a pipe wrench on a couple, but I'm guessing it originally came with a gadget that had three 1/2 inch studs to go in the holes and keep it from rotating? Had the same situation on my Model 20 snap couple disk and assumed the previous owner had welded the plates on. Now thinking it was welded from the factory that way.

Thanks Doc !! I'd take you up on it but it would be a long drive from the middle of Michigan to New York and back. Is that a fair description of what it looks like and does? I'll make one from the odds and ends piled in my shop.

Perfect! Thank you for the pics and the measurements. Spent the last two days putting in rye, much of it using the 175 pulling snap coupler disk and a cultipacker.