Okay, so I know I have stock gears in the truck, it's an 06 with the 4.6l with CAI, and Custome tunes, however my question at the moment is, what should be the best gears to put in and how much does it cots on a 4x4? Please keep in mind the truck is constantly underload but the gas mileage and the uphill is absolutely horrible.

 

I have 3:73 in mine, but it is a 5.4. I would like to go with 4:10 for a little more pep and pulling power... I think it will end up costing around $1000 for a 4x4, but I'm not 100%.