The S&W PC shop drilled and tapped the frames, not all at first but eventually. The TCs were shipped with rubber S&W logo Hogues, for the big hands of the Germans. The distributor or an individual would add the Nills. Frames that were not drilled or tapped would have been done over seas.
Of my three export/imports, only two are drilled and tapped. The 5906TC had rubber Hogues. While cleaning it I notice it was drilled and tapped. So I ordered a pair Nills for it. The 4006 Limited is not marked TC but it is drilled and tapped and had the Nills on it when I got it. The he 845TC came with the Hogues and is not drilled and tapped.
Front to back, 845TC, 4006 Limited and 5906TC
Joe