I have a 02 f150 4x4 v6 5 speed.
I average 16 miles to the gallon.
I am looking at changing from stock 3.55 gears to a 4.10 gear ratio to try to improve my mpgs. I have 31s on the truck now but am considering switching to 33s. Will this help? also if i do the swap i am considering installing a limited slip in the rear and a locker in the front. Pros/Cons
Please help
also any other sugestions on how to improve mpgs will be greatly appriciated.
also considering cold air intake and electric fan swap will this help?

 

3.55 to 4.10 conversion will kill your mpgs

 

Unfortunately you can't have your cake and eat it too. Bigger tires and wanting better gas mileage is an oxymoron. There are a few things you can do to preserve it a little and more importantly reduce transmission stress and keep power, with the V6 you need all you can get. If you're moving up to 33's look at a 4.30 ratio. Look up Gott's mod for an intake modification. Efans will help some. A tuner (Xcal 3 from VMP tuning) will make a good improvement also.
As far as the locker, it depends on what your goals are with it. Is it going to be heavily off-roaded to warrant the need for a full locker or would limit slip do? With a locker in front it will need to be disengaged every time you want to turn. Hope this helps.