May be an Empire but it hasn't been found in any Empire Parts Lists so far. Besides the 9, 10, 40 and E507 there is a B10 and a few few others of this style. Wm E. Pratt had a No. 7365 in their catalog (see Rathbone Vol One page 385) and may of made the others marked with the implement companies own part numbers
I would still classify your 9 (or 6) as an orphan till a parts lists shows up listing it.