The barrel will not be numbered but a 1943 Colt barrel was marked "Colt .45 Auto" on the lower left side of the chamber, just above the link lug and "P" on the link lug. Probably an "F", "N", "D", or "7" on the bottom of the barrel; maybe a leftover "G" barrel depending on when in 1943.
A High Standard or Flannery Bolt barrel would definitely be a replacement, as would one with Colt 45 Auto on the top of the chamber.