I know this question has been asked before, but I've been unable to find if it has been answered

I'm trying to find the spec for the mounting of a manual chuck as fitted to the ORAC. I've taken it off, and it's a 3 bolt flange, located by a short taper. It looks very much like the fitting used by EMCO, but without one to compare it with, and my inability to resolve mental images to much more than 50 mm, I was hopeful that someone might know the definitive answer
