I am looking at a 2000 F-250 ext 4x4 with the 5.4 gas. right now it is stock but i have plans if i get it to level it out and put 35's on. im pretty sure it has 4:11 gears in it factory not positive thought. im just a little worried about what the gas mileage will be with these gears, while i know if im worried about gas puttin 35's on it wont help at all. im sure ill get better in the city with the gears but wont the highway suffer bad if i run over 60?

ANY input on these trucks will be appreciate