I just got my two newest home, and my 66-4 3 inch is serial range CAU, product code 102715, Spec. Ord. 6069, finish S, stock SB, features MAG-NA-PORT. I don't understand the SB under stock, it is a round butt, but in SCSW it lists black blade front sight-1994 also for SB, but why under stock.
Here is a picture of them together, I will post better pics later when I have time.