NPS as him listed as Reuben T Justice, further digging indicates he enlisted Sept 10 1862 somewhere in Tennessee. Shown as absent without leave July and August of 1863, having stayed in Vicksburg after July 4. He then is listed as deserted in Oct Nov 1863. He took the oath and was released Feb 1864, in time for Prices raid.
https://www.fold3.com/image/88565720

He would have been 24 or 25 when he enlisted...