If you know his name and the aprox. Date of birth,& live on the U.S, you can look him up @ the social security death index. From it, the death date and someother info can be given in order to get his death certificate and possibly an obituary. Go to: ssdi.rootsweb.com
My mother died in 2004 how do I find her social security number?
Since he is a Veteran, you may be able to have his records pulled from the archives.You could try this link and follow the steps, it may or may not yield your answer vetrecs.archives.gov . Also, here is the home site for that link www.archives.gov .If they send you the DD 214, it should have his ss# on the top right hand corner, at least that's the way mine appears, and I got out in 1993.Best of luck to you.