Are you looking for this Caleb? Wikitree ID Sylvester-1164
who died in Townsend in : Sylvester, Caleb, Maj., b. in Scituate, m., a. 92 y. 6 m., farmer, Apr. 7, 1846, old age. Vital Records of Townsend, Massachusetts, NEHGS, Boston, Massachusetts, 1992, p. 330
Townsend records say: Caleb Silvester & Family from Hanover (Massachusetts) 1798 p. 436, but doesn't list family members names
New England Historical and Genealogical Register, Volume 86, 1921, p. 127 list the children of Caleb Jr. and Abigail Jacobs, but no William.