I serviced the oil cooler on our 85, 6.9 junker we got a few weeks ago. The big orings were rock hard and broke apart in pieces, no life left in them. I am still cleaning the system out as there was oil in the coolant reservoire.
But when going over the truck and trying to look over the engine, I definately found contaminated coolant, but I do not recall getting a hint of coolant and nasty mix of gunk in the coolant system with the oil? It was always black tar, no foaming at the dipstick, etc.
Things are looking ok in our situation, but your post caught my eye.
Our oil cooler was definately shot and mixing things, but I didn't get coolant leaking through the engine like that at all?? Are our trucks different or should I have got this leakage automatically if my oil cooler was shot?