Another excellent book written by the factory Historion Roy Jinks is also shown and I have it as well and I highly suggest it as a Great choice. Here is a direct link to the Factory letter I spoke of and the Excellent reference book the Poster before me mentions that can be ordered from your computer and shipped to your front door.

Please confirm the serial number on the bottom of the butt and we can go from there. In 1969 they changed to 'R' prefix serial numbers beginning with R1.

Some models are not as fast selling as others and although a reference book shows serial numbers and list's years when they shipped, it can only be considered a general idea of that model as I have seen some that shipped several years after these books show them to due to a less Popular status or demand for them. The serial number can tell you the range of dates that the gun was made, and the specific year. According to the Standard Catalog of Smith & Wesson, the Model 60 was first produced in 1965 and shared serial number with the other Chief's Special models starting at about serial number 401754. The Only True way to know when your gun was shipped from the factory is to apply for a Factory letter. I see another responder has Pointed out an excellent source of S&W serial numbers and it will provide many hours of good reading on all the different models they made and make.