Crown gear number decoding (what gear Ratio)

Not me and to tell you the truth I don't know how that could be because that 2-10-72 is the date of manufacture. That's a date code your looking at and nothing else.

It's so simple (and much faster) just to count the teeth on the crown and ring gear and divide that's what I'd do. Divide the # of teeth on the crown gear into the # of teeth on the ring gear. For example if the crown gear had 10 teeth and the ring gear has 40 teeth you divide 40 by 10 and it comes out to a 4.10 gear set.