Ford super duty 3.31 rear end. Will it be a big mistake. ?

Lantley wrote:

4x4ord wrote:
^^^^At 25000 lbs and on 7% grade a 475 hp truck will pull down to about 58 mph. The difference in 3.31 gears vs 3.55 gears is this:
If the truck with 3.55 gears and 34” tires will be running at 2600 rpm in 6th gear it can put out 475 hp.
The truck with 3.31 gears and 34” tires will be running at 2800 rpm in 5th gear at about 56.4 mph and it will be putting out about 462 hp.

But if the hill gets a little steeper the 3.31 ratio equipped truck gains hp as it slows down where as the 3.55 equipped truck will loose power as it slows. So really both gear ratios will perform extremely well with loads under about 18000 lbs. once you get into dually territory 3.31s are no longer as desirable nor are they available.

Are you basing your logic on towing a 25K loaded RV? Not many if any are towing a 25K RV. But maybe you are referring to a 25K GCWR which is a realistic figure.
But if 34" tires are required to prove your point, you are stil not providing real life scenarios.
So far I'll stick by my comments that the 3.55 will deliver a better towing experience simply because it will hold gears a little more while going up the grade and be less likely to downshift. 3.55 may also get you started a little easier.
But if your towing with 34" tires for some reason::? 3.31 maybe better:@

Yes my math is based on 34" tires and 25k lbs combined weight. With a ten speed if you find yourself towing in a situation where the transmission is constantly shifting in and out of 10th you can simply lock out tenth gear ... or even nine and tenth if needed.