I have a new working theory. As I’ve done all these parts swapping and replacing what part has always been on the bike when creaking and not been on when silent. I thought that answer was rear wheel, but now with new rear wheels, still creaks. Ah, but I moved the cassette from the old wheel to the new one, and when I used my rear Areo wheel and the bike was silent I used the cassette on that wheel not the one from the creaky wheel. The DuraAce cassette has the two largest sprockets attached together with a composite core to make one piece. Then the next 3 sprockets on another core, and individual sprockets after that. So today I tested is the creak dependent on which sprocket I’m in when cranking hard. Yes. Only creaks when I’m in the two largest sprockets. Next test sprockets from the Areo bike cassette on new wheels.