There are at least three ways to find out this info. The easiest is to call the factory 1-800-331-0852. Or you can post on the S&W forum http://smith-wessonforum.com/eve or you can buy the Standard Catalog of Smith & Wesson.
What hberttmank said. While you can get a guesstimate from a table in standard Catalog or other book. the official word has to come from S&W either a verbal answer or a letter ( $30.00 from Roy Jinks S&W Historian) S&W did not send out or make guns in strict numerical order. I know one collector that has 2 guns with almost consective serial numbers but the letters say that they left the factory almost 10 years apart. In S&W anything is possible.