The M-1967 USMC LCE was one of those nylon webbing gears for the Vietnam War. About the difference between the M-1967 USMC and the Army M-1967, just read this: Story About USGI Buttpack. Long words in short: the M-1967 USMC and the Army M-1967 are definitely two systems, you shall not confuse them.
Judging from the real objects, M-1967 USMC gears’ contract number are all dated 1970 or even later. But the US force started withdrawing from the South East Asia since 1969, the M-1967 USMC only had little chance. The real objects show that the M-1967 USMC gears were still issued at a number, some of them show the signs of being used or even modified.
But in the other hand, gears being made in the war time always in large number. Think of the M-1961 buttpack, it stayed in the supply and logistics system even in the 1990s. So that I believe the M-1967 USMC may be the same.