It is a S&W Military and Police made shortly after WWII. The "S" indicates that it has the improved hammer block developed after an AD from a dropped revolver on a Navy vessel killed a crewman in 1945.
The number under the crane is a company fitting number to keep parts together in the factory. It has no meaning after the gun has been completed and a serial number applied.
I won't guess a dollar value. It won't be extremely high, these are common guns and yours has a lot of flaws in the finish. On the other hand, the Magna grips from this period are worth a bit of money themselves and add to the value of the gun if they are numbered to match - in pencil on the inside.