I am trying to install a new shower head but the old one is stuck. I've removed the shower head itself but there is a ball nut that allowed the shower head to swivel attached to the pipe from the wall that will not come off. I have tried WD-40 but it will not come off. The shower head was installed in the early to late 70's. It looks as though the ball is a complete second piece, but is it a part of the pipe? Does this ball come off at all or do I have to cut the pipe and go from there? Help!

If it were me, I would cut the ball off the shower arm, stick the handle of my channel locks inside the shower arm and use brute force to back out the old shower arm.

Chrome shower arms are cheap compared to the aggravation of trying to reuse an already ancient and corroded fitting.

I agree with growler, The swivel ball is attached to a collar that screws onto the pipe stem get some vise grips and muscle it off