Downunder, What you say seems to be true. In ca 1980 the standard for measuring S/N ratio changed, to give everyone bigger numbers to brag on. I think then Exclusive re-defined the P3 to P3a with maybe some minor changes, if any changes at all. No one seems to know for sure just what changes would have been made at that time.
Personally, I wonder whether one CAN have too many great turntables, and I feel that I am testing the hypothesis.