Labor guide says its over 20 hours work, the instructions don't say take out engine but it says remove timing chain/timing cover. I heard fellows at the dealership take the body off The Lincoln Navigator to replace the timing chain and h/gaskets but I have never done one. Best to ask your question on a Ford specific forum.It's a huge job, I don't think you would want to tackle it at home.There is a company that independent auto repair shops get their information from, this same information is available inexpensively for people that work on their own cars.. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online
you can do it in the truck after removing bumper and radiator and all other parts in front of engine. you then have access to remove front of engine components. make sure you have all the tools and get ready for a long two days.