Don't run the thing if you jack it up! If you have lockers or posi, it'll drive right off the jack!
Mud and a gas pedal will usually do the trick too. Just get someone to watch or set up a video cam. Just remember that unless you have lockers, it's not true 4WD, one tire per axle will usually get power, the other wont. That stops you from sliding all over the road when it's wet. When you go around a corner, the outside wheel has to make more revolutions than the inside. That's why they stopped making solid axles decades ago.