The snap rings will differ in thickness by individual differential assembly. Each diff case, carrier and output bearing (s) are very slightly different simply due to manufacturing tolerances. The snap rings account for this, in very small increments, in order to get the proper preload on the output bearings, backlash, and pinion/crown gear mesh patterns.

Hopefully by mixing and matching your available rings, you can get the adjustments right, or close enough. I’d start with the OE rings that came with the new diff carrier. Left side first, then right. You may need a punch, or the old race to get them to seat. Then check backlash if good, check the gear tooth pattern. Try a different combo if not to slightly shift the diff crown towards or away from the pinion.

Not sure about the different casting numbers on the crown, but count teeth on your pinion and crown and divide to get the ratio. If it’s the same as your OE ratio then the numbers on the crown don’t matter. Maybe factory or some other identifying mark?

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