I also had a grandfather in the 96th infantry division who died when I was little. I know how you feel about not knowing anything other than what the discharge papers say and a few tales (probably "tall") passed around by older cousins.
If you didn't know already, the division association has a website: http://www.96th-infantry-division.comhttp://www.96th-infantry-division.com which has some good general information. There you can also find the text of the Presidential Unit Citation which was awarded (as Uncle Bob pointed out) in January of this year.
You should sign the guestbook on the web page, as well as send a note to Don (a former Deadeye) who is the division historian and who also runs the website. Don was in Company "L" of the 382nd infantry regiment, by the way. The division still puts out a newsletter called the "Deadeye Dispatch" (not sure how often - probably once or twice a year). Don can include your grandfathers name in the next issue. It's possible (although _extremely_ unlikely) that there's a Deadeye out there who remembers your grandfather. It's worth a try, but don't get your hopes up.
Also, if you are really interested you can get a day by day account of the 96th during combat by aquiring a copy of "Deadeyes: The Story of the 96th Infantry Division" from Battery Press for about $50: http://www.sonic.net/~bstone/batteryhttp://www.sonic.net/~bstone/battery
The book they sell is a reprint of the original (copyright 1948), but it has all the same information.
If you want, I would be happy to photocopy the page or two which has information on the activities of the 382nd on April 8, 1945. It would be easier if you knew the company he belonged to. Most likely whatever company he was in when discharged was not the company he served with on Okinawa (my grandpa was in company "I" of the 383rd infantry regiment during Okinawa, but was discharged from company "K" in Feb. 1946), so I may as well get everything pertaining to the regiment if you're interested. My life is pretty hectic right (moving) now so I can't do it for a few weeks.
Best wishes on whatever you decide - let me know how you make out.