Interesting about total interchangeability being achieved about the same time that the tolerances were relaxed to the point that Colt no longer felt it necessary to number the slides.

Other than a post WWII rework in which numbered slides would have been arsenal fit to other pistols including different manufacturer's, would a earlier numbered Colt slide interchange with say a Remington Rand frame if done randomly in the field during WWII? Perhaps a field armorer could accomplish this?

I know that Colt numbered slides were sometimes mated with Colt frames that were slightly off by a few numbers after leaving the Colt factory.