If the man in question lived in Tennessee for another fifteen years or so, he may have responded to the questionnaires circulated among Confederate veterans.

Does the 1890 census indicate that Moody Young ever served in a different unit?

1861 enlistments for the 6th Tennessee Regiment ran for twelve months. At that time veterans eligible for military service under the law of Apr. 16, 1862, had to reenlist for another two years. They could remain in the same unit or join a new command. Also, before passage of the law, men enlisted for twelve-month terms were offered cash bounties and furloughs to reenlist in new units. If Moody Young reenlisted before the law went into effect, it might help explain why his record with the 6th Tennessee is so brief.

Looking over the names of soldiers in Tennessee units, you will notice that several are simply listed as 'M. Young'. Others include a middle initial. One of them can be found in the 6th Tennessee Regiment. It's possible that one or more of them could be Moody Young.

It will help to know where this man lived in 1860, and his age at that time.