Welcome! The model 64-1 fits with the D prefix serial number, but the barrel and cylinder sound to be replacements, likely from a model 66. Does it have a fixed or adjustable rear sight?
The OHP model 64s in .357 were fixed sight 4" guns. The 164xx is a factory internal code used to keep parts together during assembly and have no meaning outside there.
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Alan
SWCA LM 2023, SWHF 220
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