Model 10-5 is the .38 Military & Police Tapered Barrel.
Model 10-6 is the .38 Military & Police Heavy Barrel.
These are among the most common revolvers, built on S&Ws medium 'K' frame in various generations for the last 111 years with several million manufactured.
Serial number C660687 dates it to 1963-1965. Serial range for those years was C622700 to C810532.
Value is probably around the $350 mark, a gun or pawn shop will offer considerably less as they need to make their profit margin when reselling.