Taurus PT-22, when did the "lock" arrive?

[MedWheeler]

Just curious.. I have recently acquired a secondhand PT-22 that does not have the "Taurus Safety System" lock feature.. wondering how old it could be. I'm at work now, so I cannot provide the serial number offhand; if anyone knows how to date them using that, I'll add it when I get home tonight. But for now, when was the TSS added?

 

[Taurus 617 CCW]

I can't nail down a year but Taurus didn't put locks on their guns in the 70's and 80's. The 90's is when everything went standard with the TSS lock. My best guess was somewhere during the 1994 AWB.