Up until now I have usually ordered my blades from the dealer, but have decided this time to try out a couple of online companies due to lack of "dealer customer service". I can't seem to match my OEM blades with the ones offered on different websites. My OEM blade from Toro is part number 105-7781-03. It is for a z453 52'' side discharge. Since I can't find an exact cross-refrence number, my questions are: 1. Most of the websites offer the right size blade but with a 1/2 in hole instead of a 5/8 inch hole. Can I take a drill bit and make the hole larger? 2. Does it matter if the new blade is heavier, and thicker then the stock blade? Will this effect the way the mower is able to turn the blades? 3. According to my measurements, from one tip of the blade diagionally across to the other one I am measuring 17 & 13/16 inches. I'm assuming this is a 18'' blade? Thanks guys!