As much as you might not want to hear this; I would purchase a new power steering pitman arm. The power steering arm has the number 3741383 (usually with an "A" or a "B" after the number) cast on the arm.
The ball stud is hardened. So if it was loose in the pitman arm socket, it will pound on the tapered hole that is machined into the arm. So even if you seem to retighten the ball stud into the original pitman arm (and it seems tight) the "fit" of the taper is no longer proper between the two parts and I would be very concerned that the connection could loosen with some driving.
I would be safe and purchase a new arm.
Let me qualify the above with one more statement. If the castle nut was loose, but you still had to use a tool to "break" the taper fit between the stud and the pitman arm, then the tapered hole in the pitman arm would still be correct and you could go about just retightening the connection.