All models were made in both blued and stainless versions. The differences are in the sights and grip frame.
Security Six: Adjustable sights, square butt, 2.75", 4", or 6" barrel.
Police Service Six: Fixed sights, square butt, 2.75" or 4" barrel.
Speed Six: Fixed sights, round butt, 2.75" or 4"...