I have about a 4 year old 60" Hustler Z which had the older style saddle type blade spindle set-up and offset blades with only a 1/2" arbor. I ordered parts and converted my spindles to the newer saddle-less design so that I could use the new fusion blades. I also enlarged my deck's discharge opening to make it like the new decks per the plans that mowerconsultant e-mailed me. I completed the job last night and I must say that with the new fusion blades and the enlarged opening, the mower cuts like it never has before. I mowed somewhat wet grass last night which was very long - about 8" - 9" - down to 3". It cut right through it and left no grass blades uncut. It also dispersed the clippings really well considering the grass was so long and wet. I was running doubles before I converted my deck. The doubles dispersed the grass a little better, but did not leave nearly as nice of a cut. I am thinking about buying another set up fusion blades and running doubles with the new set-up just because I like to tink with things, but I don't see nearly as much of a need for doubles as I did before. I highly recommend to anyone without the new style deck that you enlarge the opening and get the new fusion blades (you will need the spacer kit, too and most of you will not have to upgrade your spindles). For me, it made a huge difference. Nice job, Hustler.