Also go to Google Books and search topics relating to the Third Army. Patton, and Army medics. You may run accross a mention of your grandfather or at least find some back story as to his experiences.
You also mention your dad's Vietnam Service... make sure he has all his information correct with the VA. My dad was a lifer in the Navy, served in Vietnam and retired in the early 1970's. He has some service connected disabilities and dealt with the VA till his death. Sometime in the 1990's the VA changed and updated computer systems and used Air Force personnel for data entry. The Navy used the standard month/day/year format for birth dates, so (not correct date) 02/11/1935, or February 11. 1935, after the computer change apparently the data entry people used day/month/year format making his birthday 11/02/1935 or November 02, 1935. Issued a new card with their mistake. He had to pay for a certified copy of his birth certificate to show the VA to file for the bd change before he could get a correct card,the VA refused to accept all his past records and driver's license.