'GIBBS, ... Zadock, s. Benjamin & Abigail, b. Apr. 9, 1727'
His sister Sarah was born Jan. 1727. Even if that was Jan. 1727/8, it is unlikely that Zadock as born Apr 1727. Apr 1723 (as given in the Genealogical Register of Litchfield) fits much better in the family. It also agrees more closely with his age at death.