oil water cooler 1989 f250

I have oil in my cooling system and am told that the only way for this to happen is the (Oil/Water cooler) located above the oil filter to be broken or rusted, or "O" rings bad.
Could someone tell me if this exists, where it is, and what is it called so maybe I can replace it.
Even better could you give me a better idea of what the problem might be.

Thanks
Butch

On the windstar.....this is an optional item.
The FORD listed repair is to replace the oil cooler that screws in-between the oil filter and the normal oil filter mounting. This is how it is installed on the 3.8L windstar engine. It has 2 tubes that connect to the cooling system (water).

On the windstar.....this is an optional item.
The FORD listed repair is to replace the oil cooler that screws in-between the oil filter and the normal oil filter mounting. This is how it is installed on the 3.8L windstar engine. It has 2 tubes that connect to the cooling system (water).

Thanks, I know where to look and what to look for now.
I will probably be asking for more help later.

Thanks again
Butch