Naw... I think that this tool most likely started life as a No 4. Since it has two patent dates, that narrows it down to a type 9 or 10. If it has a frog adjustment screw (can't tell from this angle) that would put it at a type 10, since that feature first appeared in the type 10's. Doesn't matter, though, since the bed is ruined! It's been broken in half and ground down to a smooth edge. :lol:
Can't tell what vintage the frog is, since you can't see the shape of the top arch (or whether is has a frog adjustment screw). The lever cap, cap iron & blade look pretty good, though. The lever cap is even the un-embossed kind, which puts it at type 12 or earlier. The tote would be nice if it didn't have a giant crack right in the middle!
It does kind of look that picture of a 10½ on B&G, but those rabbet planes have a blade that's shaped kind of like a "T" on the end, with the width of the blade extending out on each side to the very edge of the plane. Not so with this one... :-?