I have 3:54's with the 6spd. and consider the gearing marginal. Any less power and I think I'd definitely be wanting the 4:10's. Unloaded the 3:54's are great but I'd sacrifice the 1-2 mpg for the towing comfort any day. Don't let the 4:10's go because of mileage, they'll more than make up for it if you add larger tires or tow.