S&W was not using model numbers that early. It was factory designated as a "Chief Special." They were extremely popular and probably didn't spend much time in stock, so yours probably shipped near its date of manufacture. Only a factory letter can tell you for sure, but that will depend on how much you "need" to know. It does appear to be in the range of the early Chief Specials and too late to be a "Baby Chief."

Froggie