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BUT, the fact that no one is calling the J-20s powered by WS-10 as "J-20B" and instead it's being called "J-20A" --- imo means there are only two possibilities:
1. Production J-20s powered by Al-31s are called J-20A, and production J-20s powered by WS-10s are called J-20A as well (only change being powerplant, therefore no change in variant -- per the J-11B and J-10C examples).
2. Production J-20s powered by Al-31s are called J-20, and production J-20s powered by WS-10s are called J-20A (change being powerplant and some sort of other possible internal changes in the aircraft that we are unable to externally identify).
However, I see no permutation of possibilities based on past patterns and based on what we know of J-20, for us to believe the idea that the J-20s powered by WS-10s are called "J-20B".
I fully agree and - maybe I need to work on my English ? - that's what i tried to tell him: There is by all understanding even if I personally would use a different system NO J-20B yet.