Have I missed something in these posts, or have you failed to post the serial number (the entire number from the flat portion of the frame to include pre-fix, and suffix letter stamps); I have also failed to note any descriptions of engraving/s or lack of engraving thereof. Without this most basic information, we can't help you at all. As to the "SD4G" barrel marking, that stamp (actually SD & G) denotes a company and distributor Shoverling, Daley, and Gales. Also, the patent stamps have nothing to do with ship date, gun age, grade, or value; these stamps merely represent the patent grants under which all LC Smith guns were manufactured.