just a thought but if you run an 8 3/4, what i do is cruise with my 2.76 and throw in the 3.91's for the track. after a few times it only takes about an hour, and by the way my car came withe 3.91 which i love, but when i put the 2.76 in for a road trip, i also loved them..... awesome, i'm gonna get one of everything, or at least a 4.10 or 4.30 or 4.56 with a spool with my spare housing.