Gotta break down and buy the S&W Bible so I can look this info up. Can't tell ya how many were made but they do seem to be more scarce than the blued models. Have a 19-3 like stevieboys and love it. Finish has held up very well and its a fine shooting snub. Never liked nickel in my younger days but have come to love the finish.
I'm sure one of the experts will help you out with the ratio. Keep a good coat of wax on it, be careful with the solvents when cleaning it, store it properly and it'll look great for a long time. You will be pleasantly surprized at how accurate these snubs can be. They aren't getting any cheaper and are no longer being made plus are a classy looking handgun thats a good investment.