Any USGI 1911/1911A1 pistol that would've been found during WWII would've/could've been issued for service during Korea & Vietnam.
Colt, Remington Rand, Ithaca, Union Switch & Signal mfg 1911A1's.
Often these would be as issued in WWII or arsenal refurbed with 1950's vintage parkerized Colt mfg military contract slides. Common replacement barrels were Colt mfg, HS [High Standard mfg] and F marked [Flannery mfg] USGI barrels.
You might even find WWI vintage 1911's that had been refurbed in military arsenals in service. Likely, these would be parkerized vs blued and being retro fitted with WWII era Keyes type dark brown plastic grips. Arsenal refurbed pistols will usually be stamped [i.e. AA for Augusta Arsenal, SA for Springfield Arsenal, BA for Benecia Arsenal, etc]
The correct Vietnam era holster will be the 1916 pattern leather holster in black with US on the flap. Common maker of these was "Buchheimer"; "Bolen Leather Products"; "Cathay Enterprises Inc", "Nordac Mfg Corp"; and "Hunter [Leather] Corp". Or the WWII era brown leather 1916 holster that had been retro dyed black.
NAA.