Hall tailpiece photo, please. Until then, you can only claim that nothing about the Hall body, as seen from the top, would indicate that it can't be a Buckner. By the way, the Rainbird brass popup body had a 4-inch overall height, in its final version. They all standardized that dimension about 40 or so years ago. Rainbird did offer a popup with a stainless steel piston for awhile, and it might have a bit more popup height.