when i had to find some custom belts for my SC setup/pulley upgrades and whatnot, i checked www.dayco.com for their parts catalog, found what i needed, then called them. then they connected me to a private distributor located in chicago by the name of BJ, and you can give him all your info over the phone and hell shop it to you. dayco only ships to businesses so i had to order it through BJ. pretty nice guy and company to deal with. just ask for him if you find that dayco makes what you need..

but damn, a 12 rib belt? that fucker must be wide. good luck.