Sorry to hear about Roy. We all will eventually make the "last muster". The only thing I can suggest is contacting the division veterans association. They may be able to put you in touch with someone who served with him in the 21st. I'm including phone numbers but it's best to write.
3d Marine Division Association 7622 Highland Street Springfield, Virginia 22150-3931 (703)451-3844
3rd Marine Division Association 978 Larkspur Place North Mount Laurel, New Jersey, 08054-4952 (609)235-8178
You can also contact them through the website at < http://www.caltrap.com/http://www.caltrap.com/ > (click on the address to go there). You might also want to post an obituary.