Lancaster County, Pennsylvania Will Book L, volume 1, page 260, from 1812
Jacob Shallenberger, decedent
This is only an index. https://www.co.lancaster.pa.us/1068/Will-Index-1730-1977
FamilySearch - Search.
Pennsylvania Probate Records, 1683-1994 Lancaster Wills 1810-1821 vol L-M
pages 260-262, Will of Jacob Shallenberger
https://www.familysearch.org/search/collection/1999196 (Browsing Collection)
This has the will images.
Jacob appears to be the secondborn.