A Mod 40 lettered from 1961, sold to the original Charles Daly company, N.Y.
Note the 4 screw frame discontinued starting in 1957. The frame is stamped Mod 40.
I recently sold this gun to pay some high veterinarian bills for my dog Gunny (see avatar). The shine on the right side profile picture is not wear, it's poor photography.
I did hold on to my low 4 digit Centennial Airweight (lock screw) and my Mod 640. Something had to go, so it was this one.