4" stainless 686-3 - BEC14xx
Snubnose blued Model 36 - 758xx
Snubnose stainless Model 60 - 16Xxx (the third digit is actually "X")
BEC14xx = 1989.
On the 36 and 60 take the serial number from the underside of the grip butt. See pic.
Since they are both steel framed they are safe with +P.