That's a Hogue grip attachment bracket hooked on the grip locating pin.
L'LS, any parts replaced at the factory will have a diamond stamp.
Once you get a factory letter; Firearm History Letter Request - Smith & Wesson (at S&W website)
Firearm History Request - Smith & Wesson
you can apply for records here:The Smith & Wesson Historical Foundation (SWHF) has digitized and indexed records for the years, 1932-1941 so far,
Smith & Wesson Historical Foundation