I received the above (below) statement last week when I went to HQMC Historical Branch in the Navy Yard, Washington, D.C. They hold most of the operational records of all Marine Units serving in Vietnam from 1965-1971. It is amazing that each of us can obtain, without cost, a complete operational history of 3rd Battalion 5th Marines from 1966 to 1971. The history includes the initial deployment of the Battalion in the spring of 1966 to Okinawa, through Deckhouse I to the final return of the Battalion from Vietnam in 1971. This history is reflected in the Monthly Command Chronology
outlining key events that happened during each month in country and in After Action Reports of major operations. Each CD includes an index outlining all 108 total CDs in the HQMC collection. Additional CDs can be order for $10. plus shipping cost from the Marine Corps Heritage Foundation at the same address as the Marine Corps Historical Branch. 
Some operations which our Battalion participated in during your tour may not be included in 3/5 records because we were under the command of another unit. If you wanted this information, recommend you buy their command CD from HQMC or contact your 3/5 Company Representative.
JD