Hello again and thank you for the additional information. It is important for you going forward that you know exactly what forum you were tried in and also exactly what the outcome will be because you will be asked by prospective employers if you have been convicted of a felony or misdemeanor and details, and you will have to have the answer. In addition, you will just want to know for yourself, as you do now.
So, what I would recommend is that you personally request a copy of your military service record from the National Archives. You can do that by going to: http://www.archives.gov/veterans/military-service-records/
You should get a clearer picture of what forum you were actually tried in (I suspect that it wasn't a GCM--hopefully I am right) and what kind of discharge
you received. That has to be your starting point. If by some odd chance the Archives come back without anything, then there has been a major mix up someplace. Then you have to decide if you are going to contact the Department of the Army or let it lie. The problem with not doing anything, is that something can pop up when you least expect it. The truth is that an National Agency Check (FBI background check) should turn up the court-martial and the report of the AWOL periods.
You would not be eligible for GI Bill
benefits unless you can produce a Honorable Discharge
DD-214, which will not be the case for you.
Please let me know if you have specific follow up questions. I would be more than happy to answer them for you.