crashband 7: 1980. Serial number range was 57K0001 to 91K6800.
Zippo7883: 1952. Serial number range was K136691 to K175637. Assuming your gun has a ramp front sight then it is a Pre-Model 18, the K22 Combat Masterpiece.
rusherbob: 1974.Serial number range was 7k1 to 7K26043. The other number is an 'assembly number' used to track fitted parts as they moved around the factory.
J A: 1990, probably around July, as BFL 1101 to BFL1535 is recorded for that month. Some of the three letter serial prefixes are out of date sequence that year, so it may have been made earlier or later, but that's the best guess without paying $50 for the S&W historian to look your gun up for you. The 686-3 was made from 1988 to 1993.