See pic for the correct location for the serial number.
The additional stamping of the SN in the frame cutout was only done for a few years.
On the older Smiths, say pre WWII and some after, Serial#s could be found
on the barrel just above the ejector rod, inside the crane cutout, on the back rim of the cylinder, on the bottom of the butt and usually on the right panel of the wood grip. It seems that as the Smith revolvers went from 5-screws, then 4-screws and finally 3-screws, the various positions of the Serial#s were dropped, but never on the butt.
Love the 5-screws! And the diamond grips numbered to the gun!