The 4th ed. of the S&W Catalog refers one to the Model 50 for information on what I believe you have. It's called the Chiefs Special Target, 2 or 3 inch barrel with micrometer click rear sights. These are marked as M-36 or M-36-1 or have no designation at all and approximately 2136 were produced. I'm sure there's someone out there more knowledgeable than I who will provide more information, possibly more accurate. ion, I jumped in too quickly, the 36-6 is, indeed, a target version produced in 1989 as a special production with a 3" full lug, with ribbed barrel, ramp on ramp base and a wide smooth trigger. However, it doesn't provide any number produced.