Difference between 4.30 & 3.55 gears
My 2011 F-350 has a 3.55 geared rear end. The new 2017 F-450 only comes with a 4.30 geared rear end. Basically the same engine (6.7 turbo diesel). Does that mean better or worse fuel consumption...
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I'm guessing that even though there is a big difference between the two ratios, the final gearing in the tranny will compensate for a lot of the difference and you'll see maybe a 2-3 MPG diff empty and probably only about 1-2 while towing if even that much. I drove a ram with the 3.42 ratio and then my 4.10 ratio and the best I could tell on the factory tach there was only about 250 RPM difference at 60MPH. I'm sure the fords are similar. That's why I went with 4.10s, easier on drivetrain too with the lower geared set.
