John Thread and Elizabeth King
Your John Thread and Elizabeth King (married in 1791) are also in my family. I saw a site on the web that said that John Thread's father was John Threadgir (born in 1739, died Jan 27, 1767, and married a Sarah in 1758. John Threadgir's dad was J. Threadgirl.
Elizabeth's father was John King, married to a Mary. I have no proof of this, though. Do a search for "Jane Colyer" on the familytreemaker site. She was the grand-daughter of your John Thread through his daughter Jane Thread (who married Edward Colyer). Maybe that will help.