I am new at this, but need some professional help..can anyone tell me the length of the blades for the Big Bee 72 Finishing Mower, it takes three blades and mine need replacing so I would like to have new ones on hand when I start the project of changing them....I understand from reading some of the post the bolts are 3/4 inch , left hand turn....I have really learned alot and enjoyed reading this Forum..many thanks!