Want to change gears in front and rear differential but need some good information before I do this. I tow a 15000# fiver from Pa to Az. and have been told to change to 4.30. Then again I was told not a good idea that I should go to 4.10. This has really got me confused. They say 4.10 is not eenough but on the other hand the 4.30 is tooooo agressive. I am leaning to the 4.30 because we paln to travel the East side of the rockies next summer, Tetons, Glaser, Yellowstone etc. Any help will be appreciated. 2002 F350 7.3PSD, stock tires, Stacks, K&N, Gauges, Auto, Etc.