I'd put it in the mid-'60s. What does the cylinder release latch look like? Is it flat or does it have a knurled beaver tail? If it's flat that puts the ship date somewhere around or before '66.
The number on what you called the cylinder arm is a factory assembly number that has no purpose after the gun is put together.
Thanks for the welcome. It has the knurled release. So I guess it would be around the '68. Thanks guys.
Should have joined a long time ago. I've never have good luck trying to date my S&W. I always seem to get the ones that fall in the gray areas, missing letters or double letters not found on the lists.
Thanks again,
Gary