2.94 to 3.37 is enought jump to change MPG on the highway, esp on long road trips. Unless there is different Transmission gears for the Big Tow package in the final ratio
and this is true about there not being a posted differance between between the two , i think there could be some buy backs in the future....
here is a kwel site if any one wants to atempt the math:
http://www.smokemup.com/auto_math/index.php