From taking your photo and enlarging it, it's pretty obvious that this gun has been rebarreled with a cut down 6 1/2" barrel from what probably was a pre model numbered 1950 Target Model. The Smith & Wesson roll mark is right up against the muzzle and not centered on the barrel. From the photo, there does not seem to be a match in the bluing between the barrel and frame/cylinder ass'y. The serial number range for the Model 26 (1950 Model .45 Target Light Barrel) ran from S76212 thru S211000. This would include pre model numbered guns manufactured before 1957 I do believe. Production ended in 1960. The Georgia Highway Patrol Commemorative Model 26-1 was manufactured in 1988 with 800 produced.
The gun is, in effect a Frankengun and not rare. That does not change the fact that it may be a very good shooter. The N2845xx serial number is a post 1957 gun which means that it is stamped with the model number adjacent to the yoke, on the frame below the front of the cylinder window. Swing the cylinder out and inspect that area. In all likelihood, it started life as a Model 25-2 (1955 .45 Target Heavy Barrel) but it could be any N-Frame Smith. Because of the above, it's pretty hard to place a value on the gun. With specimens such as this, it's value varies from one potential buyer to another but the gun definitely has no value as a collectible or rare specimen.
Bruce
