Hi, Mike !
You´ve got a pretty fine "early" one, with the maker marked on the blade, ("later one´s" were maker-marked on the crossguard).
The M3 trench-knife was manufactured between 25th of March 1943, till August 1944.
From July 1943 on, the blade was parkerised, (before: blued), and the M3 was used with the M8 and the M8A1 scabbard, (before, with the M6-scabbard, made of leather).
Apx. 10 maker´s in the US manufactured, (est.), more than 2.500.000 knive´s.
Reibert, Thanks for the info on my knife, even with the internet I couldn't find the info you just provided me. I like to know as much about these things as possible, I really appreciate the info.
mike nice find!! thats the one i was looking for,iam still looking!!