Daniel, as Mr. Adamski noted, a majority of the Army/Army Air Force records for the WWII era were lost in a fire. However, if they had confirmed that your grandfathers were among those lost, it would seem they would say so, rather than requesting additional information. It also seems odd that they have not requested a serial number. Did you make your requests on a Form 180 and make it clear that he was a WWII vet?
A couple of suggestions: If your mother or father (a child of this grandfather) is living, have them submit the request online as next-of-kin. That can be done at this address: http://www.archives.gov/research_room/vetrecs/http://www.archives.gov/research_room/vetrecs/ Whether you submit in that manner, or re-submit a Form 180, try to include his serial number. Your odds of success will be greatly improved if you can do so. Some places to search for the SN: 1. Look for his discharge with other important papers (birth certificates, death certificates, etc) stored in safety deposit boxes, or the like. Also, if a family member has any letters he wrote home during the war the return address on the envelope should have his serial number and unit. Have you visited his grave? Sometimes it is on the headstone. 2. Check the public record repository (e.g. county courthouse) in the town/county to which he came home. Many WWII era vets recorded their discharge (or other papers of separation). 3. Check with the Dept of Veterans Affairs service officer for his place of residence at the time of his death. If you can't contact that person, try the DVA main phone for assistance 1-800-827-1000. If he ever applied for/received benefits, they should have his SN in their files. 4. State Historical Records Office (of state where he resided at time of entry into service). Ask them to check service record cards, bonus records, and Reports of Separation that the state may maintain. Internet listing of state historical record coordinators: http://www.archives.gov/grants/about_nhprc/state_coordinators.htmlhttp://www.archives.gov/grants/about_nhprc/state_coordinators.html Internet listing of state veterans affairs offices: http://www.va.gov/Partners/stateoffice/index.htmhttp://www.va.gov/Partners/stateoffice/index.htm 5. Any employer to whom a record of military service may have been furnished. 6. Veterans organizations to which he belonged (e.g. American Legion, Veterans of Foreign Wars, Disabled American Veterans, etc).