Are focusing screens for the 3 RB itterations all interchangeable? (Pro, ProS, ProSD) :confused: The reason I ask is that KEH lists several, and specifies some for certain models. However, I have done a search of Mamiya's site, this site, other photo sites, Googled and Yahoo'd, and come up with nothing other than the feeling that they are all the same. One thing that could be, is that the earlier non "S" or "SD" didn't have the mechanism that made the horizontal red bars come up under the screen. (And - I could be wrong about that) Maybe the screens were different on those. But still, are they interchangeable anyway? Sorry for making a new thread, but nobody addressed this in the prior thread.