Where is the model number on a S and W 357 mag?

There are more than a dozen different model numbers of Smith & Wesson revolvers that are .357 magnum caliber. The Model 60 is a 2 inch 5 shot .357, and the Model 66 is a large frame 6 shot target pistol. Model number is based on frame size, type of sights , and the material (blued steel, alloy, stainless steel, etc. So there is no ONE mdl number.