SmithBuyer, There's two types of Model 1905, 4th change sent to Australia in 1941. Neither would have any special markings - just the standard S&W markings. They are (1) a commerical gun ordered by an Aussie distributor, or (2) a military gun sent to the Australian military. If the gun is
the 2nd type, and that's what the letter says, and was "liberated" from Aussie ownership by an American GI who brought it home after WW2, it would never have been through the Aussie rebuild of these guns and obtained the numerous rebuild markings seen on Aussie guns. As said above, the letter has all the info. the factory knows about the gun. I would give the gun a slight value increment to a Victory collector, over guns with the Aussie rebuild marks, as they are refinished and can have mixed numbers, and yours is original with a letter.
Ed.