I have a three month old '21 F-350 King Ranch dually 6.7L with the 3.55:1 able ratio...👍
I was REALLY hoping for a steeper gear, 3.73 or even a 4.10 based on my '12 RAM 6.7L dually with a 3.73. But the 3.55 is doing a GREAT job!
The Lie-o-Meter says on long unloaded trips in just over 19 mpg and towing at 70 mph I'm at around 9 mpg and at 60 mph I'm around 10.2 mpg. Around town normal daily driving I'm in the mid teens. I checked two tanks actual compared to the truck computer and the truck was about .3 optimistic...😀 Your mileage may vary.
My rig is on the heavy side, maxing out at 18k# triple axle. I can excelerate to 70 mph on freeway entrance ramp ready to merge smoothly when I hit the freeway. Once I'm on the freeway I'll adjust my speed. 👍 I could not do that with the RAM, not even close. But almost 200 hp and 250 torque more, things happen a lot quicker.
I really don't think you can go wrong with the standard 3.55 ratio.
Mine is not an electric locker, but I know when I lit the tires up in front of my neighbor's driveway, I left four black marks. I was empty and only did about a foot in length, but I just had to do it...👍 As they used to say "the Devil made me do it..." 😀
Good luck with your new '22!
PS: Forgot to mention the 10-speed transmission. This transmission is the greatest thing since sliced bread...
Don't let the low 3.55 ratio fool you, this will keep you always in your power band.
The first gear is 4.7:1 and believe me, it gets things moving very fast and smoothly. Just about like the granny/creeper gears in the old 4-speed manual truck transmissions. I'm very happy with how it performs...
First - - - - 4.696:1
Second - - 2.985:1
Third - - - 2.146:1
Fourth - - - 1.769:1
Fifth - - - - 1.520:1
Sixth - - - - 1.275:1
Seventh - - 1.000:1
Eighth - - - 0.854:1
Ninth - - - - 0.689:1
Tenth - - - - 0.636:1
Reverse - - - 4.866:1