new tow vehicle question

we are trying to find a new tow vehicle-a Ford Expedition. I have found one with the heayy duty tow package but it has a 3.31 rear axle ratio instead of the 3.73 ratio. the tow  package has a transmission cooler, a heavy duty radiator , the wire harness for brake controller and hitch.

We plan on taking the Rpod on long distance, cross country trips-eventually driving from NC to Calif and even to Alaska.

What do you think the difference in axle ratios really means?/ Is it power, torque, gas milage, longevity???

Should I continue to search for a TV that has the 3.73 axle or take the 3.31??

Thanks for any input.

Vann

Different manufacturers have slightly different axle ratios, but in general they are close to:

3.3-3.4, higher speeds possible, less torque at low speeds, best mpg

3.7, best middle-of-the-road gearing, better low-end torque but still decent mpg

4.1, best torque for heavy loads but worst mpg, very high rpms at highway speed

For the heavy duty towing vehicle you describe I would go with the 3.31 for use with the pod, it will only be about 3000 pounds when loaded.  My Suburban is similar in specs with the heavy duty towing package, 6 speed tranny, 3.42 rear and I've never wished I had a different ratio.  Very happy to get a little better mpg day to day.