Sources & Information:
Lead in Info as quoted:
"The following from <genforum.genealogy.com> is suggested by Shubnah Rich, in his (East Truro--Cape, that they [Jabez and Dorothy (Ellis) Gross removed to Maine, which was probable inasmuch as Jabez's elder brother, Thomas inherited most of his father's estate, and others in the family were living in Maine. They may have returned, about 1791. Jabez Gross came with his family to Otsego County near the present Cooperstown, then practically a wilderness. Otsego County histories say that they came from Cape Cod. He and his son, Crowell, made large purchases of land, as recorded by deeds in the County Clerk's Office at Cooperstown. Gross Hill--still so called (1961)--at Garrattsville, near Cooperstown, shows the probable location of their farm lands. There is no record of daughters, although there are said to hve been six, and five sons."

Gross Hill Cemetery, New Lisbon, NY., visited on June 19, 1985, by Virgina Schoradt, the New Lisbon Town Historian. Cemetery located west of Garrattsville, NY on Vibbard Road, near the old Tobias Maginnis Farm. Has a low stone wall around it - not mowed. Condition: fair. The following markers were located:
Gross, Jabez d. Oct 1, 1858 age 74 yrs.
Gross, Betsey - wife of Jabez d. Dec 20, 1965 age 74y 4m 21d.
Gross, Alonzo - son of Jabez and Betsey d. at Southport, Chemung Co. Oct 6 1846 25y 4 m.
Gross, Mary L - dau of Jebez and Betsey d. Jun 29 1868 age 43 years.
Gross, Crowell d. Jan 2, 1847 age 82 years.
Gross, Phebe - wife of Barzill d. Aug 4, 1845 age 29 years.
Gross, Fanny - wife of Seth d. Nov. 8 1861 age 52y 8m 16d (stonedown).
Gross, Seth d. Dec 9, 1882 9(stone down).
Gross, Anna d. Jun 11, 1885 age 73 years.
Gross, Betsey - wife of Crowell d. Jun 11, 1848 age 42 yrs.
Gross, Amada - dau. Crowell and Betsey d. Jan 12, 1836 age 14 years (stone down).
Gross, Nancy Maria - wife of Ellis d. Mar 7, 1850 age 49 years.
Gross, Marvin H - son of Ellis and Nancy d. Jun 22, 1850 age 26 years.

Several Markers were recorded by the D.A.R. in 1937 but were not found in 1985.
Gross, Jabez d. Mar 26 1819 age 76 years (stone broken).
Gross, ? - wife of Jabez d. Jun 6, 1821 age 76 years (stone broken).
Gross, Amy d. Jun 6, 1821 age 75 years 11 months (stone broken). This would make her birth abt. 1746 thus potentially the dau. of Hincks Gross and/or sister of Jabez Crowell Gross. Watch this one!

Additional source information:
Page No. 49., Library of Cape Cod History & Genealogy.
The Gross families of Truro and Wellfleet, Yarmouth Port, Mass., C. W. Swift, Publisher and Printer, The Register Press, 1914. This item indicates Jabez, b. _____, m. Dorothy Ellis of Provincetown.
Jabez Crowell Gross and Dorothy 'Dolly' Ellis both died age 76 yrs and each buried in Gross Hill Cemetery, West of Garrattsville, N.Y. Stone markers located but both broken.
There have been three dates and three locations of marriage being accounted for as
follows:
1. 24 Oct 1763, Truro, Barnstable, Ma.
2. About 1765, Of Edmeston, Otsego, New York.
3. 24 Oct 1765, Provincetown, Barnstable, MA.

GROSS FAMILY REFERENCES:
1. Archives Records LDS Salt Lake City, Utah. Kelsey Gen. B9 F6 Vol. 2, Page 235.
2. Data received on Nov. 16 and Dec. 5, 1984, via letter from Ms Marion Turnbull, New Lisbon Historian, Morris, N.Y. 13808.
3. Otsego Co., N.Y., Deaths, V-1, 1790 - 1840.
4. Otsego Co., N.Y., Deaths, V-2, 1841 - 1862.
5. Otsego Co., N.Y., Marriages, V-1, 1790 - 1840.
6. Otsego Co., N.Y., Marriages, V-2, 1841 - 1852.
7. History of Otsego County - 1740.
8. Otsego Co., N.Y., Wills, V-1, 1794 - 1824.
9. Otsego Co., Federal Census, 1800.
10. Gross Hill Cemetery Records, located west of Garrettsville, near Crystal Lake, Otsego Co., New York.
11. Vital Records of the town of Truro, MA., to the end of the year 1849. Published by the Massachusetts Society of Mayflower Descendants, Boston, MA. 1933. Jabez Gross of Wellfleet and Dorothy Ellis of Provincetown married October 24, 1763, page 97.
12. Sandwich Archives and Historical Center, 145 Main St., Sandwich, MA 02563.
13. Harwich Vital Records.
14. Harwich Church Records.
15. In letter dated December 2, 1984, from Ms Marion Turnbull, New Lisbon Historian, Box 196 B, Morris, N.Y. 13808, to Edward D. Ellis, 2016 N. Vermont, Royal Oak, Mi. 48073, the following is given.
16. <http://genforum.genealogy.com>.
17. Ancestry.com > Cowles-Hennis Heritage, Public Member Tree, Unsourced. Gives date of birth for Jabez Gross as 1742, Wellfleet, MA.

Shebnah Rich, Truto, Cape Cod or Land Marks and Sea Marks, Rutland, Vermont: Charles E. Tuttle Company, reprint 1988 (1883.)
Ferguson Lothrop, "Register of Some Early Provincetown and Truro Families, "Sturgis
Library, Barnstable, MA., R974.492.
Col. Harry H. Ellis, U.S.A., Retired., The Family of Lt. John and Elizabeth (Freeman) Ellis of Sandwich, Ma., 1983.

The LETTER:

Dear Mr. Ellis:
The earliest date in the Gross Hill Cemetery that I find is 1812 a Seth Harrington. Other names listed there are Cole, Watkins, Pasko, Bunell, Herring, Wing, Denison, Bennett, Perkins, Eddy, Bennington, Peck, Wilcox, Spencer, Card, Carpenter, Barber, Patrick, Fellows, Southworth, Van Wayner, Smith and Backenstove. I would doubt that there were any descendents of the family in the area. In a personal book "1740 History of Otsego County"
I found in New Lisbon "The locality known as "Gross Hill" was early settled by a family named Gross. Ellis Gross, now at an advanced age, resides in this vicinity."
"Mr. Ellis Gross was one of the earliest inhabitants of the town of New Lisbon, having assisted in its organization. Over three-fourths of a century ago he was born in an almost unbroken forest. Mr. Gross maintained a character for unsullied integrity in his intercourse with his fellow-men. He enjoyed the implicit confidence of his neighbors, and for many years occupied, by their suffrages, the responsible offices of the town.
He represented them in the board of supervisors for several years. He took a deep interest in the temporal welfare of this entire region. Himself a model farmer, he sought by example and precept to induce thrift, good tests, and the highest success in that department of human action. In connection with his farming, he was proprietor of a saw-mill and blacksmith-shop. Crowell Gross, his father, was born in Mass. about 1762, and came to Otsego Co. about 1791, bought a farm of 50 acres, an entire wilderness, which he cleared with his own hands. In a few years he added 300 acres more. A few years after this purchase he added more, making enough to give a small farm to each one of his children.
His family consisted of 12 children, 7 sons and 5 daughters, Jarvis, Daniel, David, Ellis, Crowell, Seth, Barzell, Priscilia, Phebe, Azubah, Asenath, and Anna.
The subject of this sketch was born in 1804, in Otsego Co., town of New Lisbon. He lived with his father on a farm until he became 20 years of age. He then took a farm, which he managed very successfully for 4 years. Then he united in marriage to Miss Nancy, daughter of John Patrick; of this union were born 6 children; Marvion, Erasmus, Dilason, Orsemus, Freeman, Alphonso, three of whom are living. The mother of these children was an example of high moral worth and true womanhood to all who knew her, although obliged to leave her husband in his prime of life. Mr. Ellis Gross married for his second wife, Mrs. Roby More, widow of Col. G. W. More. Mrs. Gross had one daughter by her first husband, Hallalies More. She is the wife of DeWitt C. Davis, wholesale merchant in New York city."
This is all the information we have. Possibly the New York Historical Society, Cooperstown, New York, might have something to help you.

Yours Truly,
/s/ Marion Turnbull.
New Lisbon Historian.

Individual Record <familysearch.org>.
Submitter: Robin McNees Ellis, [address not given] Battle Creek, Mi., 49017-2325.
Submitter: James E. Patzer, 460 E. 700 N. PO Box 928, Duchesne, Utah 84021-0928.
Submitter: Harry Clifton Hadaway, 10 Timmins Road Bow, NH 03304.