I just replaced a belt on my 06 C9. I don't have the coach here, so I can't look up the number, but my cat number was the same as yours. Just call a CAT dealer, and give them the part number, and ask for length and number of ribs. I went to an Oriley's store, and gave them the specs, and got a new Gates belt, for approx 55 dollars. It was 1/10 of an inch longer, but that is no big deal, with the belt tensioner. You can get a new belt at almost any automotive store, but they can't cross it with a Cat number, as Cat is reluctant to furnish specs. on parts, so aftermarket suppliers cannot duplicate, but a dealer will tell you. Saves a lot of time and shipping costs.
Good luck
Roger