I have a '21 3.5 ecoboost with 3.31 gears and want to swap to 3.73s,
has anyone on here with a 21 changed axle gearing ?
I am curious about what programming changes need to be made, I believe the speedo uses the wheel speed sensors so;
the speedometer should still read right ?

Has anyone had their dealer do a reflash ?
Curious if they will say, yeah no problem, or if it's like pulling teeth to get them to do this.
I may have my local dealer just do the whole swap if they are willing.
( I talked to them on wed about this but, have not heard back yet )

Thanks in advance for any help.

 

You could probably do speedo with forscan