Ranks ascribed to Confederate veterans are very dicey, for a couple of reasons. First, there was a tendency use military rank as a title of respect for prominent or older men with any military service, regardless of the nature of that service or the rank held at the time. Second, there were ranks associated with holding office within the UCV. "General" Harry Rene Lee, for example, eventually became Commander-in-Chief of the UCV in 1935-36. He died in March 1938, at the age of 92. Even his Tennessee death certificate gives his title as "General," although his wartime rank in Co. K. of the 34th Mississippi was Sergeant.
I have an ancestor which was very active in UCV and Hood's Brigade Association activities in his later years, and known universally as "Colonel." His wartime rank, start to finish, was Private.
Almost a hundred years ago, an old Texas veteran with the improbable name of Valerius Cincinnatus Giles passed away, leaving a sprawling, fragmentary memoir of his Civil War service. A half-century and a lot of editing later, it was finally compiled and published as
Rags and Hope, a volume that has since become a classic among Civil War enlisted soldiers' autobiographies. In closing Giles wrote:
It is over, and we are all officers now!
It's General That and Colonel This
And Captain So and So.
There's not a private in the list
No matter where you go.
The men who fought the battles then,
Who burned the powder and lead,
And lived on hardtack made of beans
Are promoted now—or dead.
I imagine that the GAR had a similar problem, though I know less about them than the UCV.