Coastal: approx. 1953. As you probably know, the original alloy cylinders were subject to cracking, and were replaced with steel cylinders in 1954. SCSW cautions against firing any pre-37s with alloy cylinders. That said, pre-37s in excellent condition, as yours appears to be assuming the smudging on the frame between the latch and lug will clean up (and "box and papers" doesn't hurt, either) bring a substantial premium, approximately double what the steel cylinder models are worth. Accordingly, your gun is quite likely worth around $1000 or more, possibly a good bit more to the right collector, and you may want to get some other opinions at the S&W Forum where the experts hang out.