Don't worry about it. The broken head was covered up by the nut, so it would have been easy to miss. I was just cleaning them up, one of the upper arms, and I was looking at the upper ball joint, and saw that it had broken where the cotter pin holes were for the bolt. Popped it out, and sure enough it needs replacing. I went to lonestars site and they said it required a 1987 ball joint; they were pretty specific about it.
Oh well, I think I'll just find an oem site and buy one. Don't see too many 1987 originals running around. Damn new ball joints are pressed into the a-arms, so no luck in swapping those out, else I would have taken them off of my old stock ones. lol