Acquired this classic Smith a few months ago. Nothing to write home about the double action, and overall grip width is a bit bigger than I like. It is still a iconic pistol of its days. Just something fun that is not a Polymer 9 or a 1911.

Those appear to be Model 59 grips on your 39, as the panel lacks the (frame's) subtle palm swell curve.
That thingy on the left side of the rear slide is a DECOCK LEVER!My Dad carried one in LE during the '80's, dept issue. It was stainless. I like it better in blue. I put more than a few rounds through it back in the day. That heavy da trigger and thumb safety made it a super safe carry gun I always thought.