No, if you have 4wd with open front and rear differentials and get completely stuck, only two wheels will spin: one front and one rear.

If you have 4wd with e-locker and get stuck with the differential locked both rear wheels and one front wheel will spin.

Note that even if you have only an open differential, Ford (and pretty much all modern autos) have a system that will apply the break on the spinning wheel, thus generating a load on the differential that will cause the opposite wheel to start turning. So in effect they sort of duplicate the effects of a limited slip differential.

 

I've been contemplating adding one in the front, Stage3 has them on their website.

 

Well I have an FX4 with E-locker.
Good to know if I ever get stuck.
Zero snow this year so I didn't have to use my 4wd once.

 

Just got 14" of snow here, I put 300lbs of rock salt in my bed and waited for them to plow. Never put it in 4WD or Elocker.

 

My 2012 fx2 has it as a option. I have used it a few times and it works great! Poor mans 4 WD!

 

Its not standard on 13 King Ranches...but seems to be pretty common. I looked at 3 or 4 and recall being told one did NOT have it.

 

It's not like you can't upgrade your King Ranch. Putting in mechanical LS isn't cheap, but worth it.