The right one was on with the 60 inch deck. It did touch the deck at full lock, but the plastic just flexed a very small amount so I was fine with that.
I just got the left one on yesterday and we got 6 inches of snow today, so i have the snow sweeper on of course. I'll find out how the left one fits in spring! I can always remove them if I need for the mow deck, but I doubt I'll need to!