I know this question gets asked nonstop and i have searched but most answers are for a 5.4v8 and i have a 2004 f150 2wd with 4.6 v8 not sure what my current gears are but i know there a high 3.23? something close to that. But i currently have 33s and my gas mileage and power sucks to say the least. I know im going to at least 4.56s but im not sure if 4.88s would be better. I will be bumping up to 35s soon once these tires wear out. I tow my 18ft bassboat and thats about it. Would like to have better mpg when driving without the boat. Which gears do you think i should get? and what all do i need to buy to get it installed? id much rather buy the stuff my self than have the shop buy it. Thank you and if i was going to add a locker what kind of locker should i install?

 

You have a 8.8" Ford rear. What is the AXLE code on the door jamb sticker?

Regearing will improve the power, but don't count on any gas mileage improvement. You will also need a programmer and custom tunes to do it right.

 

axle code is 19 which is better than i thought it was, makes it a 3.55 non-ls. How come you dont think i will get any better mileage? im getting 11-12mpg city and highway mixed hand calcuated per tank. on my last truck silverado 2001 went from 3.23s to 4.56s and noticed 4-5mpg increase. i will get a tune eventually but im gonna wait because i dont want a canned tune

 

Did you correct the speedo/odo on the Silverado for tire size and gearing?

One custom tune won't cost that much over the price of the programmer.

 

yes i had a bullydog tuner which imo did almost nothing and was a waste of money other than the gauges, and even when it was at stock tune on a full tank of gas it would only fluctate maybe a max of 1 mpg

 

but ethier way should i go with 4.56s and what else is needed for install besides the ring and pinion?

 

4.56 is way overkill for 33" tires. Expect your mpg to drop a lot. Max I would go with 33s is 4.10.

 

really?? i have a 4.6 v8 so the small v8 and i also only have a 4 speed tranny. im going to 35s within a couple months 4.56 shouldnt be overkill at all

 

You have a 2wd, you may not be able to fit 35s. That is the max for 4wds with a leveling kit.

Also the bigger the tires, the worse the gas mileage.

 

1. I will being lifting it at least 6 inches to fit the 35s
And bigger tires does not always have to mean worst gas mileage im putting in lower gears so that i can recoup the power and put rpms back to where they would be if i had stock tires so to say. But back to my point of this thread, do i need an install kit and how much/ what type of oil??

 

If you think you will recoup gas mileage after lifting it 6 inches and putting 35's on, think again. NOTHING will improve it with that much wind and rolling resistance. Why on earth do you want to lift a 2wd and put huge tires on it, especially if you WILL be towing?

You need gears and a master install kit. If you go with an Eaton/Detroit locker you need 80w90 conventional oil, anything else will use 75w140 synthetic. It holds 5.5 pints, so buy 3 quarts.

Bullydog programmers for gas engines are junk.

 

Almost a guarantee you will have lower mileage. More rolling resistance and the tires will be a good bit heavier. That is what will kill it, not diameter. Does not matter how close you get the rpms.

 

okay i guess i was misinformed, thank you for clearing things up for me i appreciate all the advice. what kind of locker should i install?

 

I'd recommend an Eaton/Detroit.