Re: E250 2WD trail capabilities?
Turn right from my driveway currently and half the road is packed snow and half dirt. If I'm not sure to get both the rear wheels of the F250 on the dirt, the one on the snow just spins... and spins, and spins. In 2wd I will actually run out of momentum and have to back down and move over to the dirt to get up the hill.
In the Jeep with limited slip I can power forward or use the brakes to force the limited slip to engage- either way, up the same hill, one tire on snow one on dirt, the Jeep will keep going up.
That's the best real world example I can think of, but the other situation you get into is when a wheel lifts, especially in a slow situation. Crossing a ditch with the Jeep I can get into a situation in 4x4 where opposite wheels are lifted enough that I can't move forward- even with limited slip and the brake trick. With a locker in the same situation, you can keep moving forward.
Anyway, one of the owners might have put a limited slip in or any of them might have lied or assumed and told the next one. If you test- one wheel on ice, or the equivalent of ice, is a must. Most surfaces I find enough traction where I would not definitively be able to tell the truck was open or the Jeep was limited slip. You can also pull the diff cover and look at the carrier (never hurts to get fresh diff fluid).
Keep in mind too that even with a limited slip they wear out, especially with the wrong fluid. All in all it would be a good time to upgrade to a selectable locker. You can figure out later what you had and be ahead of the Explorer in terms of performance- which might make up for the weight.