Perfect! If you ask nice they may send the belt along with it. I would think that your rider would be due for another traction belt by now- if it hadn't been replaced. They changed the spec slightly on them since yours was built anyways.
Thanks to several you that posted good advice for me and support concerning my transmission failure. I now feel like I can bring my X300 up to standard again and will no longer look for a different mower all together. Yes, I am still mad at JD, but hopefully this one major part failure will soon be a distant memory and I will continue with my, somewhat obsessive, maintenance rituals and use this mower for maybe the next decade and beyond.