I think Z71 has recently been the "slightly tougher than the non-Z71" version. They add skid plates, a different grill insert and/or bumper, some badging, and slightly stiffer shocks or something. It's not *really* going to compete offroad with things like a Jeep or a Bronco. But it's a 3-ton 18 foot long SUV. It's not a rock crawler. Even the Z71 version is basically just telling people "Look, if you go camping, this can probably go through a dirt road that's got some mud and/or holes in it, provided they're not too bad."