Thanks, I think. Now you've got me confused. The serial number I gave is on the bottom of the grip strap, only visible when you take the grips off - this is the correct location for a serial number on a S&W, correct?
Now when I open the cylinder, it says plainly "Mod. 60" and on my model 15 this is the area where it says "mod 15-3". There seems to be two numbers stamped on the crane, one looks original and says "96557" while what seems to be an overstamp slightly underneath says "CD4".
Does this extra info make things less confusing. Thanks for all your help.