Hi Bobbie, I looked in the York county Historical Society library and didn’t find anything except a man 13 years ago living in Portland Texas asking the same question. He thought the D might be for Dawson and that his birth date was 25 Nov 1799. Have you found him in Tenn. prior to his marriage? Have you found anything on his brothers such as their birth year? Did you ever find Samuel as a McGlaughlin? He would have been 12-15 when he was in the WAR OF 1812. Pretty young but not impossible. Does his widow’s pension application specifically say born in York County, PA?
Give us some more info if you have it.