wow that's a first, it looks real to me, I have a bunch that I picked up over the years and none have (MOD 64). Most of mine are 64-5, Also that serial number is for a 64, maybe around from 1989 or 90. Around that time they had that bean blast finish or vapor hone finish, maybe someone could chime in with a closer born on date.

when in doubt call S&W they will tell you if it was delivered to NYPD.

Good luck with it they are fine shooters, a few go to the range with me all the time.
and some have HD duty.

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sal1911a1