I'm Getting 4.10s for my 98GT 5 speed. What are my opitions for my spedo? I read the Dallas Mustang Speed Cal doesn't work on 98 5 speeds...Also my car has 109,000 miles on it. Should i just have the rear end rebuilt? What should I expect too pay ? EDIT: I read Blackfangs post very informative, it helped me not to "Fear The Gear"