According to one article, the branch you served in, typically maintains your records for 5 to 10 years from the date you are discharged after that they are sent to the National Archives.
Try this website for information: https://www.archives.gov/veterans/military-service-records
Dear Mr. Hardin,
Thank you for posting your request on History Hub!
If you have not done so already, we suggest that you request a copy of your Official Military Personnel File (OMPF). OMPFs and medical records of officers and enlisted personnel of the U.S. Marine Corps who were separated from service after 1958 and before May 1994 are located at NARA's National Personnel Records Center (NRPC), (Military Personnel Records), 1 Archives Drive, St. Louis, MO 63138-1002. To request these records, please mail a completed GSA Standard Form 180 to NPRC. Veterans and their next of kin also may use eVetRecs to request records. See eVetRecs Help for instructions. Certain information in the records is not available to the general public without the written consent of the veteran or his next of kin. For more information see Request Military Service Records.
Next, we searched the National Archives Catalog and located the series Command Chronologies and Related Documentation, 4/1962-6/1987 in the Records of the U.S. Marine Corps (Record Group 127) that includes 4 files for the 5th Reconnaissance Battalion that may contain some relevant information. These records have not been digitized. Please contact the National Archives at College Park - Textual Reference (RDT2) at email@example.com for assistance with these and similar records.
Due to the continued impact of COVID-19, you may experience a delay in receiving an initial acknowledgment as well as a substantive response to your reference request from RDT2. We apologize for this inconvenience and appreciate your understanding and patience as we balance mission-critical work and the safety of our staff during the pandemic. Please check NARA’s web page about COVID-19 updates for the latest information. Also, NPRC will continue servicing requests ONLY associated with medical treatments, burials, homeless veterans seeking admittance to a homeless shelter, and those involving the VA Home Loan program. If your request is urgent, please see Emergency Requests and Deadlines. Please refrain from submitting non-emergency requests such as replacement medals, administrative corrections, or records research until NPRC returns to pre-COVID staffing levels. Please check archives.gov/veterans for updates to the NPRC operating hours and status. We apologize for this inconvenience and appreciate your understanding and patience.
We hope this is helpful.