I could quote the serial number breakdown from my Smith book, but it's pretty involved.
Basically, if your gun has the logo on the sideplate, it was made sometime between 1977 and 1981. If the logo is on the right side of the frame, it was made after 1980. If it has a pinned barrel, it was made prior to 1983. If it doesn't have a pinned barrel, it was made sometime between 1982 and 1988.