You often see the "caster's" marking on the aluminium grip of these 3rd pattern knives but it is not always present and it doesn't really mean much if it's not there.

One of my 3rd pattern F/S knife examples, someone at some time, years ago, has made and fitted a "first pattern" style "S" cranked cross piece. Is it incorrect and wrong? - Yes - Am I worried about it and planning to change it? - No