3906 - TDL28xx
5906 - VED15xx
TDL = 1989, I think (SCSW has TBL-TCB in 88 and TED in 89)
VED = 94-96
FWIW the SCSW has a handy hint for those who have the original plastic box for their modern S&W. The big white box end label is applied right when the box is sealed for shipment, and it has a 4-digit code after the serial number. This is a date code; the first number is the last digit of the year, and the next 3 numbers represent the day of the year numbered consecutively.