People need to realize that MPG is a product of throttle, not RPM. If you tow or do mostly city driving, the lower gear will get better mileage not worse. If you want 20s, get the 3.92 or 4.10, you won't regret it. If you get the 3.21 axle, make sure you never drive a 3.92 or you will hate your truck. IMO, it makes a big difference. Not sure, get the 3.55, but it will not be limited slip.

 

Well, if I could change it I would. However, I'm a little fearful on paying someone to upgrade it, plus I don't think the wife would be hot on buying a new truck and then spending a ton of money on all this extra stuff. While I don't have the 3.92 that I originally wanted, I'm still happy with the truck and glad I found all the options that I was looking for.