Welcome to the Forum! You've got an early and very nice Model 686 (no dash) from 1982 (according to the "Standard Catalog of Smith & Wesson, 4th Ed."). The stainless steel L-frame Model 686 was first introduced in 1980, and the model was very popular with Law Enforcement and government departments. The Model 686-1 came out in 1986. There is one sample mentioned in the SCSW that is similar to yours (s/n AAJ29xx), marked "I.S.P. XXX" with the Iowa logo, also 1982. There was a S&W recall on Model 686s and 686-1s in 1987, and your revolver has the "M" stamp in the yoke area when you swing open the cylinder so it was modified. There are collectors that specialize in LEO marked revolvers, so I would think that the value of yours would be $1000-$1200. Enjoy!