I was lucky and just found one for 200.00. The guy was tired of working on it. Well, come to find out the starter was just stuck. Critters had built a nest. Great shape.
Try 1/2" X 69 Try Tractor Supply. If it is wrong, you will be able to exchange it. That's the size my research comes up with. All I had to replace was the deck belt . If I remember right, it was a 77". Hope this helps.
