I have that joint on one of my Schons. It fits the shaft with the logo on the collar, the one that has the logo on the shaft (newer) and one with no logo
on it, (earlier) than both. It also fits my 314 1st generation.
Other than those shafts, I have no idea what else might fit. I doubt you'll have a problem with any other shafts altho I can't guarantee it.
It is a 5/16th x 14.
The standard Schon shaft should fit that pin. It is 5/16x14. I have the same one and have seen pins just like it. I emailed Evan Clark from Schon about it and he said it was a standard pin used by Schon between 1993 and 1995.
I had a schon with that pin, and it hit great, but that pin has a slightly different pitch to it. My newer shaft wouldn't screw down all the way, and I posted a thread in the "ask a cuemaker" forum and was told I would need to run a tap in the shaft to make it fit. I ended up selling the cue, so I never got to try that out.