The Triton V8 is tricky to change plugs in. There is a very good chance that you will break one or more. Use penetrating oil and let it soak in and get a broken plug removal tool and have it ready. When you install the new plugs get the new one piece plugs rather than the old two piece ones and use anti-seize on the threads.
Search Ford Explorer Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Ford Explorer Experts