I'll have to dig through my box of goodies but I know I have a 10 rib renegade crank pulley. It keeps the stock 6 rib accessory belt dia but has an 8" blower pulley dia. Its a Vortech piece not sure how the Kenny bell blower pulleys are setup on a fox. I've always used the Vortech stuff since I was trying to go fast
They use the same groove as all the other accessories on a Serpentine 302. That's why I'm looking specifically for an OverDrive crank pulley (that's what it amounts to).