Believe it or not, there is such a thing as a "drag link tool". It is a socket with a blade that will fit that slot on the end of the drag link. Just unscrew it until it falls off. Actually, a large screwdriver will work also. You may still need to pry the pitman arm ball out of the drag link, use that screwdriver!
The pitman arm has a series of large and small splines, so it only goes on in one place, so no worries taking it off and putting it back correctly. As above, you do not have to remove it unless rebuilding the box. It is a bear to remove, also!
