Has there been replacement of the PT unit I am having grinding grunting noise

Ford has had a problem with transfer cases over the last couple years. Go under the car and look at the transfer case, if you see black fluid around the pinion seal or coming from the vent the transfer case is bad Here is a link to what I mean....its a mazda cx-9 but its the same thing https://www.google.com/search?q=2012+ford+explorer+transfer+case+leak&biw=1920&bih=880&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiyvfemj47SAhUoqFQKHfouDZ4Q_AUIBygC#tbm=isch&q=2012+ford+explorer+ptu+leak&imgrc=juTHSDE0L7tWIM: