Over the years the coil spring I/J frame guns have used 3 or 4 different methods of linking the hammer spring strut to the hammer. At the very least you would need not only the hammer but the correct strut also. What are you trying to do, use the early hammer with the fine checkering in a late gun because it is prettier, or what?
The gun is a pre-model 30 that has had the under curve of the hammer altered at some time in its life. I would like to replace the hammer because the incorrect curve bugs me.