[piecesparts]

If you go to a 3.42 or a 3.08 gear ratio, you could gain some highway mileage, but it will not be greatly noticeable. You will end up putting yourself into an area low and outside the engine's power band and it will hurt your mileage. The route to the other end of the spectrum will drive your RPMs so high that you will lose mileage due to overdoing the RPMS. I found that a a 3.73 gear ratio is a great compbination for one that wants to do some rough roads and hills. I have had some experience with my truck and my son's truck on gearing and tranny combinations. We finally settled on the 3.73 gearing to get the acceleration and general road use capability.