How crazy "off road" are we talking? We used our 1-ton p/u around the christmas tree farm, sometimes in slightly muddy/soft ground, out in a grass-covered field or around a pond without any real traction issues. And as always, the more weight, the better the traction ...
Tire tread makes a difference, too.
In wet muddy conditions, softroad, standing water mud more than a couple inches deep, anything where you'd be even *thinking* to put a 4wd truck into 4wd ... a locker rear won't help -- wrong truck. We had a beater 4wd 1-ton we used for that -- the "Farmdawg."
My 2 cents, anyway.
