The serial number is typically found on the side of the frame,
either cast or stamped. On very early models, the serial
number can be found on the spine of the frame approximately 6" below
the main bearing. This was usually stamped in a spot that had
been filed flat. Knowing the serial number makes ordering
parts easier and more accurate.
If there is not a serial number,
compare your hammer to the styles shown below. Click on the
images for larger view and additional details.