Interesting. Can you measure the length of the thick part of the shaft below the ball? (i.e., from the bottom of the ball to where it enters the base). I know there are two different length shafts (1" and 1.5"), but that one looks longer than 1.5".
I'm also wondering if maybe someone may have replaced the ball, as the ball doesn't look like it fits the shaft as other Monroes do. Some of the balls do screw off (Monroe made two different styles, ones that unscrew, and ones that are molded), but that doesn't look like any other I've seen, and it doesn't look manufactured the same way as other Monroes. I'd just like to have it documented here, in case it is an undiscovered type of some kind. The tall thin style might be really nice for certain games.