It is totally the PTU. Mine looked exactly like that. Its an oily black fluid, not red and it smells god awful. Its a problem with AWD Edges but not big enough for ford to do anything. http://smokinedge.com/
They replaced it first with an after market part that didnt even make it home. Then they tried to fix the after market part and the seal didnt hold either. They finally spent the money on an oem ford part and its held up fine for the last 20k miles.