Hello,
Looking to swap out my 9.75 3.55 non LS rear for a 3.73 LS rear. I am wondering what all besides the obvious will be required for me to do this. Will I have to have my computer re-programmed to account for the different gear?

For ref, the truck is a 2005 5.4

Thanks,
Devildog101

 

yes you will have to reprogram your edge to account for the different size gears.

 

What if I didnt have the Edge? Would I have to pay the dealership to re-program the computer? The reason I ask is, if I ever sold the truck, would I have to sell the Edge with it? I would want to avoid that sense I would most likely just purchase a newer F-150 anyway.

Thank you again for the help,
Devildog101

 

The dealership can program for less than $100.

PS. I see you have fogs, which tells me it is probably a 4x4. I hope you are going to change the front diff also to 3.73.

 

No, it isnt a 4x4. Just 2 wheel drive.

 

im wanting 4.10's so when i get 35s i wont have any problems. would 3.73's be more of realistic option? and idk which one makes both tires spin when you do a burnout (ls or non ls) but i want both tires to spin so posi trac style i guess. i dont know much about rear end's just some basics. lol sorry to hijack your thread, but they'd probably bite my head off for starting a new thread.. haha i have a 4x4 though, will i NEED to change out my front gears??

 

Dont worry about the thread jack, I understand.

With 35's, I would probably go 4.10's. I have noticed that alot of guys go pretty big. If you dont already have it, you would either want a LS or one of the fancier locker units that allow you to lock and unlock when you want.

Also, if you change the rears, you would have to change the fronts to match.

What gear/diff do you have in there now? There is a door sticker decoder somewhere on this forum that will tell you if you have 3.73's and ls already or not.

Thanks,
Devildog101

 

right now mine are 3.55 and im assuming non LS since only one tire spins. and ok. i need to do it before i get the 35s. right now there 285/70 17s with good tread so im going to run them till i cant anymore. lol

 

Seems like going from 3.55 to 3.73 just isn't worth the cost of labor and parts. I'd go to 4.10's, if I were you guys.

 

I'd go 4.56's if you want to maintain the same ratio as your stock setup if you have or are going to 35" tires. I have 35's on a 6" lift and I am swapping out my 3.73's for 4.56's. The Raptor, which has 35's stock, runs 4.10's but it also has a 6 speed tranny with different ratios than the older 4 speed. I have consulted a couple of different shops as well as read a bunch of threads here and 4.56's are generally far more recommended with 35's. If you have 33's, then 4.10 is perfect and if you have the stock setup but just want a bit more oomph, then going to 3.73's would be fine. I am also going with an Eaton TruTrac LS. It is gear driven, stout, and seems to have more positive reviews than say the Auburn LS. My truck will see moderate trails and snow so I stayed away from the Detroit Locker. I have a 78 F150 that is more hard core that has a Detroit though and I love it for serious wheeling. If you have the cash, the ARB is a nice setup as well. I had a Detroit in the rear of my 76 Blazer and an ARB up front.

 

on average, how much would it run for parts alone a 4.56's on front and rear? or any gears for that matter, i dont even know where to start looking.. lol

 

ringpinion.com is a place to start. Wayne at diffsonly.com will beat their prices by quite a bit though.

 

I usually do my shopping on line to get prices then hit a local shop and see if they can match it. I look at Randy's R&P, 4Wheel Parts, and others to see what Yukon and other brands are going for. Then I see what the total price shipped to my home would be. Once i have a total cost on parts I take it to whoever is doing the install, in my case Deetz Offroad or Bayshore Truck, and see how their prices stack up. If it is close, then I go local. I like to keep my tax dollars local if possible.