It is a 12 X 11 new old stock left hand MWH propeller. The MWH part number is SMC 873. I really don't know what this fit's. I haven't seen much like it, but it's left hand, has 12 splines, and approx 3/4" shaft.

Stock # 622

According to a customer: This prop fits old Volvo model 80 & 100; Eaton model A; Muncie model 300, 500 & 501; and Perkins model Z units