Re: Navigator 4:10 gears?
I concur, any good name brad programmer can change tire size to suit axle ratio to keep your speedo in check.
Going with the 4.10s is a good move. If you're running close to GCWR with your trailer I will suggest going a step further to 4.56 gears. You won't feel much of a difference with the 4.10s. However, when not towing you'll more than likely see better mileage around town up to about 45mph, otherwise top gear cruising speed will be about 4-500rpm higher, with 4.10s it'll only be 200-300rpm higher, which really isn't much of a difference.
If you find that the highway rpms are too much, you can always get taller tires, by an inch or inch and a half to negate the higher rpms that the 4.56s will bring. Mileage will be less obviously on the highway when not towing, but around town you'll get excellent results. I also second adding a good cooler to use. Sticking with OEM tire height will of course give you maximum towing performance. I also recommend using a name brand synthetic axle fluid as well for even better cooling characteristics.
'00 Durango R/T 360ci 290hp (modded); 138,500m
'06 Pontiac G6 GT 3.5L 220hp; 44,000m
'12 Chrysler 200 Limited 3.6L 283hp; 13,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!