A buddy of mine has a LLY/Allison with a 4" lift & 35" tires. Last weekend he changed the gears to 4.56 to help tow his "toy" trailer. Everything is great now, except He cant get the speedo correct. He has the Diablo Predator tuner & it only does tire size differences. The dealer wasnt much help either, they dont have programming or anything for 4.56's. Any other way to correct this?