Research Notes:
1880 David Stoner (age 31) and Mary Stoner (age 29) lived in Martinsburgh, Blair County, Pennsylvania with father John Stoner (age 54), several children, and Wesley Zook (age 23). [1]
1889 David Z Stoner lived in Martinsburg.
1903 David Stoner died last Friday [reported June 5, 1903, a Friday, so the prior Friday was May 28] at Hollidaysburg, Pennsylvania. An obituary described death events in detail and named his parents and siblings. [2]
David Z Stoner was mentioned in an obituary for his father. [3]
[1] United States Federal Census, 1880, [FamilySearchImage], [FamilySearchRecord].
[2] Copied from a scrap-book of obituaries at a library in Blair County, Pennsylvania, page 03-22.
[3] James D. Boor, Jan Oberle, Morrisons Cove Herald, Martinsburg, Blair County, PA (1994), 26 Sep 1899, [GoogleBooks].