TTurner

The truck has not been re-programmed yet. Currently I have 3.73's and I'm looking to go to 4.11's

Carcrazygts2

So currently your speedo is off. what was the factory tire size? 4.10's are not a big enough difference. I would look into 4.56's.

TTurner

I do drive on the Interstate fairly regular. Will 4.56 be to high of a gear for the highway. I don't get great mileage as it is and really don't wanna make it worse, I'm hoping the re-gear helps

rbrais

Right now your mileage is bad because you are lugging the engine most of the time. I have 3.55's so I feel your pain and then some. With the larger tires, you won't get stock mileage back after re-gearing, but it will be better.

TTurner

Ok but is 4.56 to high? Thats why i was just thinking about 4.11's

rbrais

I was planning on 4.10's, but others have suggested 4.56's. I'm undecided at this point. Either is better than 3.55's.

A7X

Rebuilding the 8.8 and 9.75" is fairly easy... I have step by step instructions on here somewhere... May not be a thread I started. Probably a post helping someone...

There are certain specifications you need to meet... If you meet them you won't have problems, it can be time consuming adjusting to meet the specs, pulling apart, adjusting, reassembling; pulling apart, adjusting, reassembling, etc... But if you take your time to setup within tolerance you're all set and won't have problems other than unlikely receiving a bad gearset...

With a dial indicator that measures to .001" and an in.lbs and ft.lbs torque wrench, common hand tools and brass punches, make a setup bearing etc it can be done at home...

Some say leave it to the pros... I say, you gotta learn sometime if you plan on building trucks, cars etc... It's really not bad if you are mechanically inclined... I don't know why the axle building process is shunned by even some of the most learned mechanics... It's really a simple and feasible feat for the do it yourselfer if you can follow instructions and adjust properly... It's not like there's some magic bolts that you have to climb Mt Everest to acquire and then do a voodoo dance with perfection to invoke the pinion God to overtake your body through the process lol

I've had good luck with yukons in the Ford corporate housings... No noise and a good running gearset...

There are plenty of other good brands though...

Again for the sceptics... There are a specs that have to be met! If you can adjust properly by moving some shims around, torque properly and meet the specs, you'll have a perfect install... Not much to it...

Almighty

With 35s or a little bigger you will be fine, 35s and 4.56 usually run about 2k rpms at 70mph with the 5.4 in our trucks

Carcrazygts2

Alot depends on your trans you have that will determine you cruising rpm. You have 3.73's so I assume your have 4R70w with and a stock tire size of 265/70R17's from the factory. So 4.10's will put you back to similar stock numbers. 4.56's will be a little over geared but it will help tremendously if you ever have to tow anything.

'08f150stx

If you only go 3.73 to 4.10 I think you will be disappointed. Like, what did I spend all that money for? For a noticeable return on your investment, go 4.56.