ok good, its a 2005 4x4 1500 with a 4.7l v8.

 

1600-1700 rpms at 55mph, assuming her truck has the 4spd automatic tranny than the rear diff is 3.92 which is the common size for 4.7L Rams. Changing to 4.10s won't have much effect, bump it up to 4.56s or even 4.88s if your not doing a lot of highway driving.

 

i have the build sheet for the truck, and it didn't get any powertrain upgrades, except for auto tranny, and limited slip in the rear, it doesn't say anything about upgrading the ratio, so i think it has 3.55's, monday i will call dodge and find out