This particular model was manufactured strictly for the commercial market. Lan-Cay did manufacture a few different bayonets for the USMC. There was a solid tang M9 made in the mid-1990s and they also submitted bayonets during the last USMC bayonet trials that resulted in the adoption of the Ontario OKC-3S. These bayonets were in the M9 configuration but they were not marked M9. They are marked USMC over Lan-Cay on the left ricasso and have the EGA on the right. The bayonet came in a MOLLE equipped scabbard.
Just wanted to add that there is an excellent article about the LanCays (Bill was referring to) submitted for the last USMC trials.
The article is written by J. Maddox and is available here http://www.usmilitaryknives.com/jim_maddox.htm
Thanks, Carlo for posting that link. I must have missed this article. Had no idea Lancay came up with so many variations. I have one of the gray bladed standard M9 patterns in tan, and one of the 6-hole variants in black...