I have a o4 fx4 with axle code h9 which I believe is a 3.55 ls. My problem is that I read on here that when doing a custom tune on the edge, the tire size and gear ratio are set to the original ford program but its showing up as 3.73. I left it there and the truck feels good, no erratic shifting or anything, but which one is right.

 

I read a thread that mention that sometimes the edge will default to a different gear ratio rating. You should make sure on your door that if it IS 3.55 that you adjust the edge to that. Running a different gear ratio with the tuner could blow a speed sensor and give you a false MPH reading which could lead to a ticket and premature drivetrain wear. If it's not on the truck door then it is on the differential itself. So if it's 3.55 set it to 3.55. Replacing a bad tuner is better than replacing a screwed up drivetrain or truck. Good luck

 

Thanks for your reply. Ill set it at 3.55