Newbie here requests help from the old pros. Is there a telltale mark that Ruger placed on factory refinished guns? If so, where is it located? I looked at a late 1960's vintage single six today that looked too good to be true. I did a quick search on the forum but did not find what I was looking for. I am contemplating a purchase and would greatly appreciate any help on this. Many thanks for helping a ruger rookie.