You can request one from Smith and Wesson on their website.
Which model? The best thing to do it check the owners manual.
Smith and Wesson Model No. 2
You can request one at the S&W web site.
YOu need a gunsmith or call S&W and ask for a owners manual
Call S&W, want ad, on line auction.
Go the S&W website and request one.
You must follow the instructions in the owners manual or call S&W
The frame size of a Smith and Wesson model 66 is K.
No such model listed in the Standard Catalog of Smith and Wesson. You will need to call the factory.
Smith&Wesson model 14
The smith and wesson model 18-3 was made from 1967-1976.
The Smith and Wesson model 19-5 was made from 1982-1985.