Records are available from
National Personnel Records Center
Military Personnel Records
9700 Page Avenue
St. Louis, MO 63132
There was a fire in 1973 which destroyed lots of records there, but much information remains.
They gave me a link
http://www.nara.gov/regional/stlouis.html
and a phone number (314) 810-0800
To quote:
"If you are a veteran or a deceased veteran's next of kin, please consider submitting your future requests online by visiting us at
http://vetrecs.archives.gov
I used these links back in 2009 - don't know if they still work.