It all depends what you do. When I tow my backhoe around town, I need all of first gear to get the 28,000lbs rolling. I know you are not supposed to do this but everyone does something they're not supposed to. I need my 4:10's and want a brownie auxillary trans. My last truck had 3:55's and did 80@2200rpms. I forget what that was at 55, but the new owner is consistently getting 18-19mpgs. He drives real easy and isn't in any of a hurry. That is a '92 f250 4x4 natural,e4od, reg cab.For a highway driver, 3:08's would rock and your 2wd 5 speed would make them shine I'm sure.