wooden propeller

[dd2first]

the propeller in question has the following number on top of each other,DES 690, NO.5257,A.T.O.537, it is a 69 in. long, with 6 holes,5 1/2" hub, 2 1/4" shaft, it was presented to Clyde Stemmermann, in St. Louis,Mo. We are trying to identify what it was used on and when. I am new to this type of forum so any help is appreciated Dave D. Owensboro, Ky.reach me at dd2first@aol.com and thanks

[Dave]

Could it be stamped "69C" rather than "690"? That would make more sense.

When I get home in a few days I'll try to cross reference the ATC number, which might clarify things.