Ok, I'm not looking to debate the 3:73 or 4:10 decision, but what I am asking is why do people suggest a 3:73 with a 5 speed and 4:10 with an auto when it's just the opposite from the factory?? The 05-06 came with a 3:55 if it was a 5 speed and 3:31 in an auto...If the car is NA, what is the better decision and way to go?

 

The 1st gear in the 5r55s auto is steeper then the 5spd manual therefore you will see Ford recommend steeper gears for the manual vs auto.

 

Personally I am going with 4.10s with a 5 speed. The only difference i have found between 3.73s over 4.10s is MPGs and from what I can tell, the difference is very minor unless you are spending all your time on the freeway.

All of the people that I've read about posting on here with 4.10s (whether NA or not), have not regretted getting them.