I don't want to argue with your personal experience as it could be correct as things change and are not consistent thru the yrs on most products.so how many times have you replaced bearings/seal on a 575? There is no seal inboard the pto bearing. the seal is integrated with the bearing, like a standard dust or grease seal.
As I said before I will say it again, mine came out from outside the case and was a straight forward deal. The seal was bought at a local dealer in Grand Rapids and they never asked for any model year info or anything else that could have indicated that the 575 model had differences in them, but as I stated I'm not one to argue with others personal experiences as when I have in the past I was wrong on occasion .