I have spent little time on the McClintock family, but my information states that Mary was the daughter of Daniel McClintock and Mary, and that her Grandparents may be Joseph McClintock (1720- ?) and Elizabeth Torrence b abt 1724. Does this match with your information?
The date of marriage I have for Mary McClintock to John Peal is 10 Sep 1795 which I found in a biography on their son Jonathan found in "Old and New Westmoreland, Pa." I am not sure of the location of their marriage, but Franklin County, Pa will abstracts suggest it might have been Franklin County.
Book A, pg 165. Will of Daniel McClintock, Chambersburg, w/w 25 Jan 1790, w/p 6 Feb 1790.Wife Mary. Daughters Agnes, Margaret, Mary, and Jane McClintock, each ¼ share when they arrive at full age.My smith tools to be sold.Exec: John Tharn of Guilford Twp, and Matthew Wilson, Esq. Of Chambersburg.Wit: Robert Boyd, John Baxter and Matthew Wilson.
Book A, pg 310.Will of James Devor, Southampton Twp, w/w 24 Mar 1794.Mentions land lying between his son John Devor and James Peel (James Peel is almost certainly thefather of John.They lived in Southampton Twp for some time, and certainly in 1800-1810).
Would be interested in anything you could provide for the McClintock family.