Oil filter mount leaking

We have an '05 Escape 4 banger that has a bolt-on oil filter mount that has a large round black plastic piece on top of the oil filter mount. The mount bolts to the block, houses the pressure sending unit and the top piece has 2 water lines attached to it.
This part has a single bolt running through it that fastens it to the mount, and is leaking oil.
What IS this piece? An oil cooler or water heater? I've yet to find what it is, if it has an o-ring sealing it or do I have to replace the whole unit (looks pricey!)..

Any ideas on where to go from here?

If its like my F-150 was its for oil circulation. It would be a dealer only item.
Go to Ford parts department and ask them to pull it up on micro film. Look at the picture on the computer screen and pick out what you need. Either gasket or o-ring buy it while your their. If something else is broken I would try a scrap yard. Either way you will need some parts from the dealer.