Dear Mr. Villa,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located Station Lists, 1942 - 1953 in the Records of the Adjutant General's Office, 1917 - 1985 (Record Group 407) that may include information about units assigned to Cebu. We also located World War II Operations Reports, 1940-1948 in Record Group 407 that includes records of many units that were stationed in Cebu. For more information about these records, please contact the National Archives at College Park - Textual Reference (RDT2) via email at firstname.lastname@example.org.
Photographs of various U.S. Army, Navy, and Marine Corps activities dating from 1940 to 2007 are in the custody of the National Archives at College Park - Still Picture (RDSS). Many of the World War II photographs are indexed geographically and have captions that may indicate some of the units or activities in particular places. Please contact RDSS via email at email@example.com to request a search for photographs of specific locations.
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 and RDSS. We apologize for this inconvenience and appreciate your understanding and patience.
In addition, we searched online and located the following which provide information about US Army activities in the Philippines during World War II. Although neither mentions the Southern Institute, they do indicate some of the units that operated in the Cebu area.
We hope this is helpful. Best of luck with your research!