I asked about flasher location in another thread on here and was informed that flashers do not exist on my 2011. I already had purchased a flasher that was supposed to work
www.Superbrightled.com doesn't show a turn signal flasher for 2011, but fordparts.com shows a flasher but I can't tell if it is for the hazard lights or the turn signals. This might be one of those questions you have to ask a dealer.
http://www.fordparts.com/Commerce/CatalogResults.aspx?y=2011&m=Ford&mo=Expedition&initSearch=1&keyword=turn signal flasher#Search