There were multiple Israel Hollands.

 1. Israel patented 29 Sept 1760 108ac HOLLAND'S ADVENTURE, a resurvey of Wms
 Luck. His son Wm Holland sold 19 Sept 1763 to Joseph Collins. Source:WORL:130
 in Colonial Families of the Eastern Shore by Wright, v8,p145 "Family of
 Richard Holland" which further states that this Israel was probably SON OF
 NEHEMIAH of Richard. (This source also mentions that Nehemiah bequeathed 
"Dubling"/DUBLIN? to his son Richard.) 
 [This Israel was grandfa of signer Isreal. This Israel died before his son Wm sold the land in 1763.]
 
 2. http://delawareday.delaware.gov/information/ratification_bio.shtml  
"Israel Holland (d. 1798) of Baltimore Hundred was a member of the House of 
Assembly in 1785 and 1788, and of the Delaware convention that ratified the 
federal Constitution in 1787. In 1782, he served as the tax collector in his 
hundred. He was a farmer whose property was assessed at £9 in 1789. The 
inventory of his personal possessions at his death totaled £218. (SAC Probate
 Records; SC Levy Court Assessment List, 1789, DSA.)"

[d.1798 is wrong. The probate was settled in 1798 but the death was
1790. Another DE.gov site lists the 1790 date with birth 1750]

DE Probate Database d 1790, est settled 1798. Calendar of Sussex County Probate
 Records as: Israel Holland Admin. 26 Apr 1798 to Matthias Aydelott and wife Elizabeth, late Elizabeth Holland.

AGBI: 
Israel Holland   Birth Date: 1750,  Birthplace:	Delaware,  Rev.War, Vol:82,Page:86   

"Aydelott Family Records", p812 (Ancestry.com) found by Nancy Merrill 
birth date 03 Oct 1750 for Israel Holland who m Elizabeth Derrickson 1772 and 2nd Matthias Aydelott by 1798.

http://delawareday.delaware.gov/information/ratification.shtml (found by Nancy Merrill)
Delaware Ratifiers of the U.S. Constitution
 	  	Birth	  	Death
Sussex County
John Ingram	  	 	  1798
John Jones	  	 	  1798
Will Moore	  	 	  1821
William Hall	  	 	  1793
Thomas Laws	  1753	  	  1807
Isaac Cooper	  	          1821
Woodman Stockley	   	  1799
John Laws, Jr.	  	 	  1788
Thomas Evans	  	 	   
Israel Holland   Oct. 03, 1750    June 19, 1790
_____

Israel Holland who ratified the Constitution is SON OF WILLIAM HOLLAND: 

Sussex Will Made : 27 Dec 1775;   Will Probate: 22 Jan 1776
Heirs: wife Elizabeth Holland; sons Israel, Benjamin, William,
Marmaduke, John and Lemuel Holland; daus. Elizabeth Holland and Rhoda Godwin;
Perry Robinson.

Land Records of Sussex Co DE, 1782-1789 abstracts by Mason and Wright lists 6
 deeds where Israel Holland is mentioned, sometimes a witness as "Esq." and 
 sometimes as "Atty".
p40  f 259 Deed 16 Mar 1786 From Ebenezer Evans yeoman of Suss to Israel
 Holland, ESQ of Suss: Evan had by MD patent of 22 Apr 1773 tr "Bear Trap 
 Ridge" formerly in Wor Co but now in Suss, which he sold by bond to Wm Holland
 of afsd county and state on 16 Apr 1773, 122 1/1 ac. Wm Holland died leaving
 Israel Holland his heir. Wm Holland Attys: George Mitchell Esqr, Rhoads    
 Shankland Esqr, Phillips Kollock Esqr and Mr. David Train. Wit: Wm Lockwood, 
 John R Hazzard, Elihu Bredell. Ackn 3 May 1786.

Land Records of Sussex Co DE , 1789-1792 abstracts by Ardine, p48 f: O-14:120.
  Petition of Rhoda Godwin, Admin'x estate of Thomas Godwin, late of Suss, 
dec'd. Thomas Godwin by Bond of Conveyance w/a penalty therein mentioned, 
agreed in his lifetime to make good and sufficient Deed to Pearson Onions, a tr 
in Balt. Hd. afsd county who has since died. Sd Bond being assigned to Israel 
Holland Esq. Petitioner requests Ct to direct her to convey sd land in 
discharge of sd Bond of Conveyance. Petition granted & order made 5 Nov 1789. 

Land Records of Sussex County, Delaware: Various dates, 1693-1698, 1715-1717,
  By Mary Marshall Brewer, p40 (found by Nancy Merrill)

Israel Holland of Sx Co 162 pounds sold to Thos. Godwin of same Co a messuage 
of land called Woodmans Folly in Little Neck 153 1/2 ac which was purchased by 
Capt. Wm Holland of Wm Hazzard of Sx Co & Wm Holland did by his will bequeath 
the tr of land unto John Holland and John Holland d intestate and without issue 
and land descended to his brother & sister wherefore the afsd Israel Holland 
being eldest son of Wm Holland dec.d eldest bro to John Holland the right of 
acceptance was vested in him with one water mill. 
 
Also, p. 50 Vol. D, Sx Orphans Court (found by Nancy Merrill)
Came into Court Israel Holland Petition (1 Apr 1783).  Marmaduke Holland died 
intestate unmarried & without issue leaving brothers and sisters Your 
Petitioner, Benj. Holland, Jacob Holland, Rhoda Godwin, Elizabeth Holland....