There are 3 sizes of DEERE stamped steel wrenches 6 3/4", 9" & 11 1/4"; they were replaced by the series marked JD-50 through JD-53. Both series are shown on pg. 132 of P.T. Rathbone's first volume of "History of Old Time Farm Implement Companies and the Wrenches They Issued.."
The ones P.T. shows have a round "hang hole" -- yours is solid, and is the smallest of the three. The example of the small size shown in Wayne Dill's John Deere tool list is solid. There are two 9" wrenches stamped DEERE -- they have different sized open ends.