Changing the Transmission for better mileage

I would think that having the tailgate down would create more turbulence directly behind the cab and more drag. Leaving it up would appear to give more of a teardrop airflow from the cab trailing down to the tailgate.

JPH

Untill it hovers out over either the tailgate or the side. (unless it gets trapped in theturbulence directly back of the cab, where it will either stay pasted to the front of the box, or float up to window height.

Your milage doesn't sound that bad. The only way to get more would be to change the differential or change the trans.. for a 5 speed or a different OD trans with a lockup torque converter