There would be no DoD rating from the Marine Corps. When you discharged back in 1999 you could have filed to have that upgraded to a medical retirement. Too much time has passed and it is highly unlikely to get that discharge upgraded.
The National Guard should have submitted you for a MEB rather than just giving you a medical discharge. How long were you mobilized with the NG? When did you get off of orders? What happened at SRP when you were getting off of orders, did they attempt to retain you on active duty for a MEB?
I got off AD in 2015 and went guard. I was 100% in 2016, I was nondeployable within 6 months of going in the guard. I never mobilized with them. I had a mini stroke and started having seizures in 2016. It is secondary to ptsd/tbi. They discharged me March 23, 2018. They lost all my civilian and VA records that I sent in. They told me that on March 21, 2018 and then discharged me on the 23rd on a letter dated March 27, 2018