Another John Walton enlisted on 4 October 1861, and served in company D; according to the Pennsylvania State Archives cards, they were different ages when they enrolled (2).
He was 33 years old when he was enrolled (2).
He was living in Philadelphia, Pennsylvania, when he was enrolled (2).
He was enrolled and mustered into service on 14 October 1861 (1, 2). He was enrolled at Philadelphia, Pennsylvania (2). He was mustered in as a private at Philadelphia, Pennsylvania (2). He served as a private in company B (1).
He was not on the muster-out roll when the regiment mustered out (1, 2).
1 Bates, Samuel Penniman. History of Pennsylvania volunteers, 1861-5. Harrisburg: B. Singerly, state printer, 1869-71. 5 volumes. 'Ninety-first regiment', volume 3, pages 186-233. (In the roster)
2 Civil War Veterans' Card File, available at the Pennsylvania State Archives, searched 29 June 2004 (John Walton)