Thanks Flyfish. Yes there are 4 numbers after the K. My revolver is in excellent shape. I purchased it around a year ago. Its finish looks almost new and it it shoots great.
range_rider13: 1985. 586s are on my short list of S&W favorites. I have a couple of them, one of which was modified to round butt. The job was so well done that I bought it thinking it had come from the factory that way.
xanth: 1975-76 according to the book, but almost certainly 1975 based on how early in the "N3" range it is.