With the N80, the trunion ball screws into the end cover. The ball has a hole drilled in it for a "reaction arm" type tool. Or I tried just using a drift. Mine was frozen pretty good. I didn't want to use heat and damage seals. I was just trying to replace plastic bushings that surround the ball.
Looks like the N40 ball is part of the end cover. There may be a set screw or dow holding it to the cyl housing, but it should unscrew.