The different versions of the CEM3372 have some subtle changes. On some synths, like the Prophet 600, there needed to be a resistor change so the later version would oscillate the same... It was recommended to not mix them. On the OB Xpander, there was a free warranty update from version B to version C because of distortion on the VCA. Almost all the Polaris's I've worked on were version B. I have a couple of tubes of the version B's that I got from Fender when they dumped all the Chroma and Polaris parts.
I don't find the version B to be a problem, but if you mix B and C, there is definitely an audible difference. Also, between the version A and B.

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