Dear Mr. Youngstedt,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located a series titled After Action Reports, 1965 - 1972 in the Records of the U.S. Forces in Southeast Asia (Record Group 472) that includes a file unit Air Assaults/Assault Helicopter Companies. We also located a series titled Aviation Unit Records, 1965 - 1973 in Record Group 472 that includes an organizational history for 1966 - 1971 of the 128th Aviation Company (known as the 128th AHC) in Box 617. In addition, the same series includes an organizational history for 1967 - 1969; daily journals for 04/01/1968 - 02/29/1972; after action reports for 02/1971 to 02/1972; and command reports for 1971 - 1972 of the 173rd Aviation Company (known as the 173rd AHC) in Boxes 636-645. The records are not digitized yet and available in the Catalog. For access to and/or copies these records, please contact the National Archives at College Park - Textual Reference (RDT2) via email at firstname.lastname@example.org.
We hope this is helpful. Best of luck with your research!