With that information, you can look for one from your exact birthday...You might get lucky...September 4th, 1986 on that one above.
Here is a box label from a 686 from 1986
![]()
Very interesting...Do you have this revolver? I ask, because I only have the 3rd Edition of the S&W Standard Catalog and that seems to point to:
104222 4" S TS RR WO, 1987-95
BTW, SB (square butt), TS (target sights/grips), appear to be used interchangeably. If you still have the revolver and can confirm its clothing/features, that would make yours one of the earliest 104222 product code, that I have seen.
The "AU" prefix definitely fits.