What is a Smith & Wesson Nickel Plated Model 29-2 44 magnum with 6 inch barrell. Purchased brand new in November 1974.
Are you sure of the purchase date and the barrel length?
The dash 2 version of the Model 29 was introduced in 1962 when S&W changed the cylinder stop, thus eliminating the screw in front of the trigger guard. This was the beginning of the 3 screw models. The dash 2 was produced for 20 years (until 1982) at which time the barrel pin and the recessed chambers were eliminated.
Nickel finish on this variant of Model 29s, while not rare or even scarce, is less common and does add a slight premium to the value of a high condition gun.
The reason I ask about the date and barrel length is that until 1979, the standard length was 6 1/2" - after that time the standard length was 6". Be sure you are measuring from the front of the cylinder to the muzzle (not from the front of the frame).
Does the serial number on your revolver have an N prefix? It should, and it would be helpful if you could post the number.