I have a JD 445 the Treads are Right Hand, These are good size Bolts, if i remember right it takes a 15/16 socket, to make them come out with out so much trouble, put a little Never Seze on the threads before you reinstal the blades, what you need to do is get a short chain, like 1/4 in. about 3 or 4 ft. long, with a hook on one end, place the hook over the end of the blade and rap the chain around something to hold the blade, i put a 3/8 in. bolt through the chain end to keep the chain from slipping, now that you have the Blade where it wont turn, take a good 6 point socket on either a 1/2 impac or a 1/2 in braker bar with a short piece of pipe for a cheater bar, i have a piece of 1 in. pipe about 18in. long that i use, when you put the blades back on check in the owners manual they may have how much torque they need, if not just use the braker bar, but not the cheate bar, i bet the bolts were put in dry last time there were out, OR some one put them back on with a impac wrench and went WAY to TIGHT, I just went out to the shop and checked the Book, it calls for 83 FT. Lb of torque, i dont ever do that because i have worked of stuff enough to know, if you are not familar with things like this, best thing i can tell you to do is tighten them up about as tight as you would tighten the lug nut on a car tire, another Thing the heads of the bolts will ware, dont let them go to the point that your socket wont catch, i change my bolts about ever 3 years,