I have a S&W Nickel plated 586 (adjustable sights) Distinguished Combat Magnum, the 581 is the same gun with fixed sights. Smith & Wesson produced these nickel plated guns until 1991 when they discontinued nickel plating and the production of both the 581 & 586. Production began in 1981, so if your date of 1974 is correct, then it would more likely be a Model 19 or 27.
The distinguishing factor for the 581/586 is the full-length underbarrel lug.
Check on the frame under the cylinder yoke, the model number should be there.
The latest blue book value for your gun, if it is the 581/586 series, at 100%, is listed as $370.00 plus 5%-10% for the nickel finish. If it is a Model 19, the value is listed as $345.00 plus $20.00 for nickel finish. If it is a Model 27, the value is listed as $400.00 regardless of finish.
Hope this helps.