There were soldiers named "John D. Gentry" that served in Company E, 22nd Georgia Infantry; and Company K, 44th Georgia Infantry.
The service records for the 45th Georgia Infantry show a "Daniel Gentry" with Company G, that enlisted in Milledgeville on 3/4/1862; was wounded @ Chancellorsville, Va. in May 1863; and died in a Richmond hospital in June 1864. The online site "findagrave" lists this soldier as "John Daniel Gentry" of Co.G, 45th GA, died 6/1/1864, buried @ Hollywood Cemetery in Richmond, Va.
I hope this helps.
Greg C. White