I know close to zero about change gears in general.
I won a lot of tooling that was supposed to be a for 13" Monarch Series 61, listed as a 15x54. The actual machine listing:
15.5" x 54" Monarch Model 13" Engine Lathe, new 1957, 15.5" swing over bed, 54" ctrs, 16 spindle
The tooling listing...