I am in the process of saving money to lift my truck higher. I am going to add a rancho 4" suspension lift to my body lift and run 37x13.50r20. What size gears would be best for me. I mostly do city driving but do drive on the highways now and then. I also want gears that will get me the best gas milage! Also, I never offroad. The only time my truck is put into 4 wheel is probably once or twice a year. Could I just regear the rearend or will I still have to regear the front? Thanks alot

 

4.88s .. you need to do both differentials as well.

 

I guess you "could" do just the rear. Probably anywhere from 4.56 to 5.13 for 37's depending on your flavor.

 

After installing the lift, wheels, and tires would i have to do gears right away or could I still run the 3.73's a little while?

 

you could run those gears forever if you wanted to. You'd get crap for mileage and be slow as hell and couldn't pull anything though...not to mention strain your motor and prolly end up burning up a tranny.

Def regear