im almost done lifting my trucking and im getting 35s and a couple of my friends say that i should get new gears like 4.56s.

are they hard to install? And how much should i pay for them

 

They've got to be done perfectly, so yeah either take them to a buddy who has done a few installs before or take it to the shop. I paid about $500 for my gears, front and rear, and had a friend of mine who knew what he was doing put them in for cheap. Expect to pay anywhere from 1200 - 1500 (front and rear) for a gear swap at the shop (parts + labor). If you have a 4x2, expect about $700 for just the rear

 

damnn thats a hella lot it seems like. will i have any problems running 35s? i have 01 screw 4x2 5.4

 

Depending on what kind of gears you are running now you will be okay. At one point or another you should re gear the thing, and not every place will charge you $700. However, I can easily see some place saying that they would charge you that much. If you got a LS rear end with 3:73's that you will be alright for awhile till you can get a new set of gears in there. If you have 3:55's with an open differential then its going to be a dog till you get new gears, which might kill your gas mileage.

 

Not to jack the thread - but I just got my truck recently and the dealer said it had a LS, so I am assuming if he was telling the truck I have 3.73s. Is there a way to verify without physically using the LS?

 

Look at the axle tag on the pumpkin of the rear diff.

 

LOL forgive me I'm such a rook.

 

Well I apologize for the newbness, I don't see anything on the rear of the differential except an 8 stamped on it. On the front I see YL3W-4028-AA and another 8. Care to put me out of my misery and explain what I am missing? Lol so embarassing.

 

Check inside your door jambs for a sticker which will tell you. Below are the stock codes with configurations.


l 18 — 3.08, non-limited slip

l 19 — 3.55, non-limited slip

l 26 — 3.73, non-limited slip

l 27 — 3.31, non-limited slip

l H9 — 3.55, limited slip

l B6 — 3.73, limited slip

 

How bad would 4.56's kill mpg's?

 

Depends on your tires and whatnot

I've got 37's with 4.88's and my mileage is about what it was (maybe a 1-2mpg less) when I had my 6" lift on 33's and 3.55 gears, but it was a helluva lot better than the 7-8mpg I was getting with stock gearing and 38's.

 

That depends on a few variables. If you're towing a lot, or have added larger tires, it may actually increase mpg's. Another common problem is people miscalculating their mpg's. They do the math based on what their odometer tells them. If your PCM had not been re calibrated to recognize the change in tire size and gear change then your calculations\odometer are off.

 

Chris - thanks a lot for that. So I have 3.55 LS... Ok 35/31x3.55 = 4.00 and some change... So 4.10s roughly. 38s would be the biggest I ever wanted to go so should I go with 4.56 just in case? I don't tow or haul much at all, this is my DD.

 

if you have 35's on you should get 4:56's.

 

35's and 4.56's is a good combination. That should put you back around how you were stock. If you have the 5.4, I would run with your stock gears and see how you like it if you go with 35's. Since you don't tow or haul much, you might be perfectly happy with it. However, if you are thinking of 38's, then you will want 4.56's at the very least.

Best bet is to ask some of the members on here that have actually changed their gears and tire sizes and get their opinions based on their experiences. Me personally, I'm running 4.56's with 33" tires at the moment. I average anywhere from 13-15 mpg with mixed city\highway. My speedometer is calibrated correctly for my gears and tires. I'm happy with this set up, but I also have the 4.2 and I do tow\haul a lot so I really needed some grunt back. My truck isn't my DD, so I'm very happy with my current set up as far as gears\tires. Hope that helps some.