I am not sure John ever said a car with the early PS ends is

a PS-0... When he first coined the term, he was referring to a very
specific all-welded, radial-roofed PS design bought by a number of
railroads.
Tim O'Connor

Tim, I'm not sure either, that may have come from Gene's CGW book.
But, as we say at work, you knew what I meant.
Clark Propst