I had the 10-6, and posted it here. I liked it, but let it go at a huge profit, and bought more S&Ws. It was in the serial range of the NYSP guns, and had the matching features. Very smooth shooter. Had I not been offered to triple my money, I would still have it. It was not marked conspicuously.
Side note: I have seen model 10-6 revolvers that were over-stamped 13.