CARL has placed the OOB for the ETO online in its collection of WW II documents. The pdf is 602 pages and 33 megabytes: http://cgsc.contentdm.oclc.org/utils/getfile/collection/p4013coll8/id/4079/filename/4089.PDF Dave
You can try Stanton's WW2 Order of Battle. It's choc full of info that will assist your search. I'm at work now and my copy of Stanton is at home. I'll give it a look later when I get off and let you know something.
We should be able to help you with your research. It would help if we knew a bit more about what you already know and what research you have done thus far. How did you determine that he served with the 393rd? Here is a discussion on this forum about the 393rd Infantry Regiment. Post #33 has a link from which you can download a pictorial history of the 393rd Infantry. The 393rd was part of the 99th Infantry Division. You can find a book on the 99th Division on Amazon or, very likely, through your local library.
It says 61 divisions assigned to the ETO, so does that include the MTO divisions, because I thought 29 were in the Pacific, and 61 plus 29 is 90.