Bindi, it's the vertical reinforcing rods at the rear of the forend that make me believe the forend is a later replacement, they are not present on my 1941 lithgows (Coachwood) but they do start appearing in 1941 production(& around the change to the MkIII*) I'm not sure if they were retro fitted at all so it being a replacement is only a quess at the mo.