All I know about differential regearing is what I learned in High School Auto Mechanics in '91; where do you start? I am going to switch to the 4.10 gears, I have a 2004 5.4L Supercrew XLT and have no idea what stock gears are, is it better to do full replacement or just do ring and pinions? Upgrades planned for summer are:
Rancho 4" Lift with 9000 series shocks
**** cepek RFC II (35X12.5)
Air Force one intake
Roush offroad dual exhaust (or Magnaflow, depends on Best Price and availability)

Some mild to moderate offroading and Trailer towing (around 7000 GVWR)

ANY help is appreciated, I am doing a LONG road trip in a few months going from Alaska to wherever the Air Force sends me via the ALCAN. Thanks in advance.

 

Read this & this about diffs.

7Kip is too much weight for a lifted truck on oversize tires. Your brakes can't handle it; your suspension will allow too much sway; & tall tires don't have the lateral stability for heavy trailers.

But you probably don't need 4" of lift to fit 35s, or new gears to turn them - you could probably just put them on & go. Take it a step at a time. Drive the tires for a while, then decide if you need gears. Lift is the last thing to do because it reduces driveability.

 

thanks for the info, I will do the lift after I get where I am going then, I have 285/70/17's on it right now and they are adequate, guess I will wait for free shipping...