Not all dealers will bite on that one! My selling dealer would not install my 4.10s, and they're the ones I bought the gears from! I've known every service writer and tech there for 12-years, but the shop foreman said no; he just didn't want to do it. Nor would another nearby dealer. I ended up going to a shop that does a lot of musclecar restoration work. They charged me a little over $400. Warranty coverage on a modification is at individual store discretion.