Jaaack I have not been able to find an "s" designation, it has the checkering in both places. Diamond shape in center of forearm checkering. and a wooden 3/16" dowel in the pistol grip running through it right to left in the "V" of the checkering. Although the rear sight is a fold down there is bluing wear in a circular pattern approx. 2" behind the fold down one. The only writing on the magazine is on the rear edge "PAT.APPL.FOR." the finish looks to be undisturbed. Thanks to everyone who replied.
