Dennis, many a Southerner has discovered a Yankee in the woodpile in his genealogy, and it always seems to come as a shock. Good luck with your research. I hope you'll visit the board often. My friends who post here are, as you said, truly awesome.
Oh, one last thing. A large number of men from the 24th Arkansas were captured at Arkansas Post on January 11, 1863. Those who were captured were later exchanged and reformed their regiment in the Army of Tennessee (Bragg's army) east of the Mississippi. Those who weren't captured formed a new regiment (Hardy's) here in Arkansas. Your g-g-grandfather was one of those who was not captured, but ended up with the ones who were, when he left the 3rd Arkansas and joined the 24th Arkansas in Georgia. It's too bad he didn't write about his adventures in the war. It would have made a great story.
Happy New Year, my friend.