JMHO, a locker can be marginally effective on mostly flat ground that is uneven side to side (pothole) or slick (gravel/wet grass). They aren‘t going to help you much when it’s an uphill/downhill scenario, and help even less so in a truck than in an SUV, unless your bed is heavily loaded. The issue is there’s not much weight over the back tires, so they just sit there and both of them spin.
I don’t mean in hardcore off-roading situations either, just stuff like going to the bottom of a dirt hill and realizing you can’t turn around so you have to back up it. Some may disagree, and it might help more on high traction area like slick rock, but I have a good amount of experience off road.
Unless there’s a particular spot you consistently have trouble like a ditch on family land, I’d skip it and just buy a pair of traction boards. If you still get stuck after using them, I’d buy a receiver mounted winch. At least you’ll be able to get out and it can be used on other vehicles.
