According to Mary Beth Wheeler's posting at rootsweb, Sands Sutton died before 1779 in North Castle.Her source is the Sutton Family Genealogy File at the Westchester County Historical Society.
I don't have any suggestions as to where to look to learn more about William Harrison, wagoner.Tell me again where you found that reference.
I looked in Carleton's Loyalist Index: under the letter "H", Harrisons are listed from pages 1055 to 1117.I read through them all - it wasn't hard because there's not a lot of info on each page.Only two seem relevant: Page 1112, Richard Harrison, List of Bills, 1782/07, Bills drawn on Harley and Drummond, with William Harrison, Place - New York; and page 1115, William Harrison, List of Bills, 1782/07, Bills drawn on Harley and Drummond, with Richard Harrison, Place - New York.Richard and William's occupations are not listed.You can read about Harley and Drummond at http://www.bopcris.ac.uk/bop1700/ref7182.htmlhttp://www.bopcris.ac.uk/bop1700/ref7182.html and http://www.tribwatch.com/DrumRoyalBank.htmhttp://www.tribwatch.com/DrumRoyalBank.htm.
I checked the British Archives website www.catalogue.nationalarchives.gov.uk but didn't find anything in the correct year range for the two names - but I only looked at the listings connected with the War Office.
I am checking all the sources I can think of.The Online Institute for Advanced Loyalist Studies does not have anything listed for William or Richard Harrison.