Not sure if this helps but it may give you an idea. Copy and paste link in your web browser. Alsodo you know the name of the unit your specifically searching for? This happens to be from the 506th they had a few units within the 3rd Brigade.
Dear Ms. Briedis,
Thank you for posting your inquiry on History Hub!
We searched the National Archives Catalog for any records relating to the 3rd Brigade, 101st Airborne Division in the Records of the U.S. Forces in Southeast Asia (Record Group (RG) 472) and located 14 series and 12 file units relevant to your inquiry. We also located 101 series, 371 files units, and 25 items of the 101st Airborne Division in Record Group 472. For more information about Vietnam War records at the National Archives, please visit our website on Vietnam War.
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We hope this information is helpful. Best of luck with your research!