Hey Wayne, first, welcome to one of the best resource websites there is. Good luck on getting your first Sport Trac. This is one of very few forums that is very mature minded. Ask a question, you'll get an honest answer. No name callin', no character assasination, just a bunch of folks thst love thier trucks.
Having the hitch(class 3/4) factory installed, does not change anything with the truck. Its already built-in. I do have to agree, that if a lesser class(2) is installed you may need to remove it, cutting wheel, torch, plasma cutter and a grinder are required. You can also get a hitch that will install under the stock hitch, so you will have 2 hitches out back. So, there's your answer. Come back soon and show us what you got! Bob