I inherited this S&W 64-1 from my father and was trying to date it. Ser. No.is D658519
thanks I'll have to upload photos. It's a bull barrel 4" .38 stainless steelThe Model 64-1 was introduced in 1972. D658519 is a 1974 serial number, so this is definitely in the right range.
A Model 64 with the 4" barrel has serial number D425963 (1972).
A Model 64 with the 2" barrel has serial number D775837 (1974).
The OP's gun and serial number are perfectly legitimate. It simply isn't accurate to say that a Model 64-1 must have a 1D serial number.