1987 or 1988 would be correct.
Don't know of a place online except to ask in the S&W forum, but the Standard Catalog of S&W shows the AY- prefix models being manufactured in those two years. Fwiw, they don't specifically list AYH, but do list AYE, AYF, AYL and AYW for 87, and AYC, AYE, AYR, AYU and AYY for 1988.