When I was a deputy S&W gave the Missouri Highway patrol officers a matched pair, a 4" 66 and a 60. It had the MSP HP emblem and their badge number on both guns. Since the MO HP did not buy them they could not wear them on duty. They were told that if the gun showed up at a crime they would be severly disciplined. Some guys sold them and some put them in a safety deposit box. I've always kicked myself for not buying a pair. Perhaps the Indiana guns were a similar thing. Date it by the SN and see if there are any LEO's from that time frame that remember them. The Indiana HP may be able to tell you if it was a gun that was carried on duty. A letter from S&W would help. If you can capture the guns history it should add to the value. I think police marked guns are very neat.