My steering box was leaking from the adjustment nut also, so I replaced it. Hopefully you can learn from my troubles that I had to learn the hard way. To remove the pitman arm from the relay rod, I oiled my largest pickle fork so it would slide past the boot and not tear it. Worked like a charm. But use the largest pickle fork, 1-1/8" I think. Also, check the threads on the new box when you get one. I'm still convinced they were mashed when I got it so I had to get a tap.
Good luck!
Larry
Good luck!
Larry