I know it's nice to have a lot of gas, but even at 10MPG freeway, thats 310 miles...on a stock rig, why are you looking for so much additional? FWIW my '83 K5 consistently got 17MPG freeway travelling across the country. Even though that MPG is bad compared to a new car, it equals 500+ miles per tank.
Not trying to be a naysayer, but is there another problem that needs resolved to make your gas last longer, or do you just hate filling up? /forums/images/graemlins/smile.gif