Im surprised you even have a LS since LS's are not available on the 2010FX4 model. FX4's come with a standard 3.73 electronic locking open diff.

 

The Internet search I did with the code L9 said 3.55 LS. The window sticker says 3.73 locking differential. I called the ford dealer I bought from and they said it's a 3.73. I called a different ford dealer and gave them my vin and they said it's a 3.55. I am even more confused now because two dealers are saying different things.

 

Well I am an idiot I must have been reading the door sticker upside down or something. The axle code on my door is L6 not L9. L6 is the 3.73 ratio with locker. I am a new owner of an F-150 and don't have much experience with these trucks or in the off road truck world. On a positive note at least I kept the thread going

 

well can you lock your rear diff? If so its obviously the 3.73 with the locker.

 

Yes it has a rear locker. I was reading another forum and people are arguing that a axle with locker can not be limited slip, it must be open differential. I remember that my window sticker said 3.73 LS w/rear diff lock. Do you think that it is only limited slip when the locker is engaged? I think it is open diff until you engage the locker, then it is LS. What do you think?

 

If it has 3.73LS w/ diff lock, then it would be limited slip until the locker is engaged, then it would be locked. If it is locked, then both wheels turn at the same speed as opposed to LS where the wheels can turn at different speeds.

 

The 3.73 e-locker is an OPEN diff when it's not locked.

 

Shotgunz is correct...you can't have your cake and eat it too! A locker is not a LS when unlocked. It is a plain old open diff...grandma's one wheel spin!

IDK if it's happening around the FX4 guys or if they don't use their trucks the same way but the Raptor boys are breaking rear ends. Not left and right, but there's been more than enough to raise an eyebrow.

One could beg the question if a locker is the best choice for the guy that spends 90% of the time on the street, and/or the guy that doesn't know how to use a locker. IMO, they should have made the locker an option and LS as standard. Even though a locker is bad *** under the right circumstances, I think the LS is much, much more versatile.

 

Maybe the front is LS. What about when 4 Wheel drive is engaged?

 

Front is open all the time, rear in fx4 open till you lock it..and in the fx4 you can only lock the rear while in 4wd.

 

And below 25mph.

 

On a sunny day, below 32C°, but not on a leap year or wednesdays...lol, sorry

 

In 4wd is it LS until you lock it or is it open all the time until locked?

 

It is an open until you lock it in. Personally, I would rather have a LS rear, but I wanted the FX4.

 

I one wheeled mine on my beach trip and on recent wet roads. I would rather have a Detroit TruTrac like I installed in my F250. It was automatic and always spun both. My stock LS one wheeled in that truck and the dealer said it was fine. I did use my locker on the beach but it was always disengaging at any speed. I could see the Raptor guys breaking them since they engage in 2wd and at high speeds.