Hello,
Production of the 686 started in 1980 which was when S&W changed there serial#'s to a 3 letter Alpha prefix and 4 numbers. The lowest known production revolver had serial# AAA0665. Regular production 686 revolvers started with serial#'s that began with AADXXXX. Have a look again at your serial#, you could be reading it wrong. Could it be AYZ00XX? If it's that serial# it dates to a revolver being shipped in 1988-ish.