You can request an owner's manual for free at S&W's website.
crimson trace grips for smith and wesson 39
100-300 or so
Request one from S&W
50- 450 usd
Check the butt under the grips.
Some older models of S&W revolvers you have to remove the grips to find the serial numbers engraved on the grip frame.
S&W's website has manuals for download or request one for free.
K frame
All S&W revolvers I have seen are serially numbered on the butt of the frame. You may need to remove grips to see it. My Mdl 36 wears a set of Hogue rubber grips, and they cover the butt.
You need to contact S&W.
500 USD