Leather Scabbard M6 for M3 knife
The regulation M3 knife and its M6 leather scabbard were introduced in march 1943. The M6 leather scabbard was made in 1943 only. It was replaced by a new plastic scabbard authorized in July 1943, the ‘Scabbard, trench knife, M8’.
(from Government Issue, US Army European Theater of Operations Collector Guide, Henri-Paul Enjames)