al31fn for replace all j10a & j11 because they don't want change too much on frame.ws10a or b for the new one.china has a lot j10a and j11 right .all the old engine soon to scrap .j11 need 2 al31f and china has close too 200 j11 and 200 j10a they need 600 engine for replace .ws10a or x for j10b and j20 .china need to use us$ on hand too
The Newest AL-31FN would prob for J-10 New Productions.
WS-10 Powered J-10 would not be ready for mass entrance into service for at least 1-2 years.
also Pak has prob ordered AL-31FN versions too.