Was wondering, I have a stock '02 2500 4wd auto w/3. 55's. I run bobtail with no load 90% of the time. A load of mulch here, 6 or 8 goats on a single axle stock trailer there are the extent of my heavy hauling. I'm avg. about 17mpg. Is there a higher speed rearend available to take advantage of all the torque I'm not using? mostly flat country roads and Interstate driving. Maybe something like 2. 90 gear? an overdrive gear for the transmission?