Dear Francisco Abril,
Thank you for posting your question on History Hub!
We searched the National Archives Catalog for "Marine Corps LVT-A4" and found some helpful info. Record Group 127 (Records of the United States Marine Corps) contains a series titled:
For more information about these records, please contact the Stills Pictures Branch at the National Archives at College Park here: email@example.com .
Due to the COVID-19 pandemic and pursuant to guidance received from the Office of Management and Budget (OMB), NARA has adjusted its normal operations to balance the need of completing its mission-critical work while also adhering to the recommended social distancing for the safety of NARA staff. As a result of this re-prioritization of activities, you may experience a delay in receiving an initial acknowledgement as well as a substantive response to your reference request from RDT2. We apologize for this inconvenience and appreciate your understanding and patience.
We hope this information is helpful. Best of luck with your research!