question on gear ratios
 

does changing your gear ratio affect fuel economy?

Yes absolutely it does!

so having a 4.10 ratio down to a 3.73 would improve it?

as long at it keeps the engine at its max torque RPM or just above during cruising. depending on how much stop an go traffic you experience, results may vary.

use one of those RPM calculators on the net to see what you will get and see if it is worth it to you. keep in mind that this change may take awhile to pay off through the savings

many difrent variables, just by chaging gears does not mean you get beter milage. but if you run motor on highway at high rpms you will probabley get beter milage.