If you can't get some gears close enough (maybe even from Jeg's or Summit) you should talk to a speedometer specialist. With my truck I installed 373 gears and the chevy dealership told me that they didn't have the right gear for it so they referred me to this guy that made the thing in about 5 minutes and charged me $60. However, now that I think about it, there's no way the adapter will fit in the tunnel but maybe there are different styles of adapters. If you do find some gears from the dealership please keep us updated because I'm sure there are more than a few guys that wound't mind knowing that information, myself included. I just had to figure out that 55 is 35, 90 is 60 and so on. My car isn't worth jack really so mileage racking up doesn't bother me any.