PJ, After working with my Hustler Super Z 66 over this year I've noticed the blade wear was different than I was familar with. I use the straight fusion blades on this unit. On my other national brand mowers the blades wear on the leading (cutting) edge until the cut quality is being affected at which time they are discarded (usually after several sharpenings). However on the fusion blade I noticed the leading or cutting edge holds up very well. Its the trailing lip on the back side of the blade that seems to catch the wear. Every Hustler blade I have discarded this year had the trailing (or up lifting) part of the blade disappearing long before the front side was worn down. Is this a characteristic of the hardened fusion blades? That is the front side is super hard and the rear is less hard metal.