Are you positive that the lift gate is Aluminum. I didnt think the Expeditions are using aluminum body panels on the expedition until 16'. the f-150 are the first aluminum bodied trucks out. everything else comes after that. I know my sisters expediton has paint coming off the rear hatch as well and looks like its oxidzed aluminum but think its actually steel. What year is your expedition?
I can't speak to lift gates, but Ford has been using aluminum skins on some of their hoods for years. I had a 2000 Ranger with an aluminum hood skin and have seen late 90's and early 2000's E series vans with aluminum hood skins, too.
