I'm pretty sure the towing package included options that did not include a steeper gear, such as tranny cooler and wiring for the bolt on receiver hitch. My truck was manufactured with the towing option, but the gearsets were yet another option.
So just because a truck was manufactured with the "towing package" or "heavy duty service group" doesn't mean it has steep gears.
Ok, I was looking at a Ram with the towing package and wasn't certain if that affected the gear ratio at all. If it had come with 4.10's then i could have slapped on a lift and tires without having to worry about gears for the time being.