In case you are unaware... Here are links to newer Nara online data bases.
Insteresting one is:
Electronic Army Serial Number ca. 1938 - 1946
This series contains records of approximately nine million men and women who enlisted in the United States Army, including the Women's Army Auxiliary Corps. Although incomplete, the records contain data for a majority of the enlistments in the United States Army during World War II.
You can search by serial number, surname, state or county. You do not need to have enlistee's serial number.
If ancestor may have settled in a smaller U.S. county.and you know the county..can look by county only and site will also list other enlistees of that county along with yours. Might find an unknown relation.
Can also search by Surname only, or Surname + State.
Here is link:
At this link are some other Nara military type data base records to search: