Realizing that every vehicle and driver is a bit different; I can say that I will never again put an automatic locker (not a limited slip ; I mean automatic LOCKING differential i.e. Detroit locker or one of its cousins) in a vehicle that is going to see slippery conditions; lived with a rear Detroit locker for well over a decade and it tried to kill me in the slippery several times (besides having the habit of allowing the vehicle to go into something approaching free fall on vey steep, mogully, descents; where alternate tires are come clear of the ground... the approaches to the Eisenhower tunnel here in Colorado can be very entertaining with a rear automatic locker since the crown of the highway is enough in some conditions to make the rear differential go sideways in the slippery.
I suspect that most new vehicle will not come with an actual automatic locker but some thing that is digitally controlled or the (overly complex and somewhat fragile on occasion) traditional GM gov-lock.
Just because the label says lock/loc or lok does not mean that it is a true locker... mostly they are trying to fool people and are some form of limited slip differential, in my experience.
I am a fan of driver actuated lockers (ARB air lockers specifically) because once locked they stay (truly) locked until released; however relatively few drivers will go into terrain where a locker is actually needed; although they do cover a multitude of driving sins...
Most recently, I put a Torsen limited slip (gear driven limited slip; avoid anything with clutches , IMO, or any thing that requires special lube or additives) into the front of the daily driven Explorer and an ARB air locker into the rear (came from Australia by slow banana boat (mostly they are in stock but mine was not) ... it was worth the wait.
BTW a locker or two is not a guarantee against getting stuck (though it can help, even limited slips can help)... the driver must still pick and follow an achievable line... and have good accessories like high traction tires. (If you are getting lockers but planning on using all terrain tires you are not going for, nor going to get, maximum traction, IMO).
Enjoy!
I had a 2008 GMC with the auto locker, and now a 2018 GMC with the auto locker.
I do understand what you mean about the automatic locking differential trying to kill in slippery conditions.
With an open differential, when one wheel loses traction, it spins, while the other stays planted, and maintains stability, though not contributing towards forward motion.
With an automatic locking differential, when one wheel looses traction, it spins, often increasing driveline speeds, as the load / friction is suddenly reduced. Then, the second wheel abruptly engages, and will often break traction as well, due to the high driveline speeds, and sudden engagement on a slippery surface.
The above description assumes that no traction or stability control systems are present, which was true on my 2008. Even then though, my locking differential never tried to kill me. The only time I ever spun that truck on the road, was after the original locker stopped locking, and I had it replaced with a TruTrac limited slip. The TruTrac engaged much differently (without delay), and I was still getting used to the difference when the spin occured.
Now, moving to my 2018. The truck does have stability control and traction control. These systems dramatically decrease the likelyhood of the automatic locking differential trying to kill you. When you loose traction, the traction control can cut power and/or applies brakes before the locker even engages. For off roading, you can turn off the traction control. You can also turn off the stability control, as long as your wheelspeed is below 35 mph.
