I would like to improve my gas mileage and am thinking of changing the rear gears. 2001 5.4L 2wd. I already drive like a grandpa so it's not my driving habits that cause the 15-16 mpg. I hardly ever pull anything so I am thinking going higher won't be a problem. Right now I have 3.55 gears. What would be the next step or two down and is it worth it? How much MPG will I gain?

 

15-16 MPG is about average for these trucks. Do you drive city highway or both? You can buy a hell of a lot of gas for the price you will pay to regear, its not worth it unless you are driving quite a bit more than the average person.You MAY gain 1 MPG or so with a regear.

 

I drive 15,000 a year and it's all interstates. I figured it's not worth it if I buy new, but what if I get a junkyard axle?