Interesting to see all the variations. I recently picked up a 1945 silver-plated BA alto, and it doesn’t have the F cup adjustment screw (nor any of the other SA features).No, that’s not a guaranteed differentiator. My 1941 silver plated BA tenor has a factory original adjustment screw set on the low F cup. They were experimenting all the time, perhaps none more so than when production was reduced to low hundreds per year during the occupation.