this won't help ya if you are keeping your old steering box, but if ya are using it as a core to buy a rebuilt one, then try this as a supper easy way to get the pitman arm off IF THE PITMAN arm puller won't work.
DO NOT FORGET TO MEASURE FROM THREAD TO THREAD on the the outside edges of the two seperate drag links outside of the threaded clamp, so you know where to put if back to when you reassemble with new box. Undo the draglink clamps, twist the tube with pipe wrench, the short end of drag link hooked to the pitman arm will now be loose, pull the box from Jeep. Reassembling this way will insure your "center" is the same, assuming you have the box at its center. Only is nascar is it fun to turn one way.
Take the 4 bolts opposite the pitman arm out, take big nut loose all the way to end of shaft to protect threads. Put box in vice, hit big nut that is on the shaft the the pitman arm is on with a Really Big Hammer. The shaft will get pushed thru the box housing, leaving the pitman arm off the shaft.
Reassemble steering box for core $.
good luck,
Jason
P.S. I do want to make clear that a pitman arm puller will be much easier, this is if that won't work.