adaher: The Model 64, also referred to as the .38 Military & Police Stainless, was introduced in 1970. It's essentially a stainless-steel version of the extremely popular .38 Military & Police (which later became the Model 10) that dates back to the turn of the century. It was originally standard with a 4" tapered barrel, then was produced with a 4" heavy barrel in .357, a gun that later got its own model designation as the Model 65.
The tapered barrel was dropped in 1973. It's not entirely clear from SCSW when the 2" barrel was added to the lineup, but it was either prior to or at the same time as the introduction of the 64-2 in 1977. There have been many special production runs of Model 64s for various police departments around the country, with the guns bearing the name of the department they were made for.
The AFA prefix indicates that your gun dates from late 1984. The 64-2 was produced until 1988, when it was replaced by the 64-4, which incorporated a number of design changes involving the yoke, hammer nose, and hand.