I know of a 1770 marriage listing for Jerusha Ward of Ashfield, MA, and Isaac Chauncey of "Cornumche",MA. Is your "Jerules" Jerusha?
I see its been suggested that Isaac was a son of Charles and Sarah (Ingram) Chauncey of Hadley, MA.This might be possible but that the Isaac listed in Fowler's Memorials of the Chaunceys is a typo for Israel.Israel was born in April 1744 in the east part of Hadley (later Amherst, MA).I'm not aware of a son of Charles and Sarah named Isaac.Josiah Chauncey, Charles' brother, did have a son named Isaac but he was born in 1755.Which leaves me puzzled as to who the Isaac Chauncey was who married Jerusha Ward in Ashfield on 19 April 1770.
An Isaac Chauncey was living in Ashfield in 1788, when he had a 15 pound financial transaction with a David Fletcher of Onandaga co., NY.An Isaac Chauncey is listed also in the 1800 census of Onandaga Co., NY.
As to Jerusha: there's a record of a Jerusha Ward born January 29, 1748, in Springfield, MA, a daughter of William and Mary (Smith) Ward.Since Springfield is just south of Hadley, maybe this Jerusha is the 1770 Jerusha.But Isaac??I don't know.
Incidentally, Fowler knew the Isaac (b 1755), son of Josiah.Fowler wrote, "He was educated for the ministry.But, becoming disapated, and spending much of his father's estate, he left home immediately after his father's death, and has not been heard of since by any of his family, and probably died in obscurity.I recollect seeing him, when he occasionally visited the Chaunceys of Durham, not far from 1808."