Apparently from:  Della Reagan Fischer's Fourteen Cemeteries in Westmoreland County, and Greensburg Sesquicentennial History, 1799-1949, authored by a committee headed by George Berry contains:   

John Silvius b. 1759 d. 1831
Anna Marie Silvius, No Data

What we know and from Mary Cole's chart:

41. John  b. about 1763  d. 1831 Westmoreland County; Called John Jr. in the 1786 tax list for Hempfield Township, Westmoreland County; Resident, in 1790, Hempfield Township, Westmoreland County; moved to Franklin Township, Westmoreland County by 1798 per the tax list; married (1) Anna Maria Yeagger; married (2) Sarah [No proof of maiden name].