I had in mind that the large frame 7020 series used the same pto setup as the 8000 series tractors. The part number you gave does fit the 8000 as well as the 77 through 7920 tractors. It doesn't fit the older 7810 etc though.

So, I guess the good news is Deere is making it possible to get factory 1 3/4" shafts down to 140 hp. Doesn't help the current problem though.