Ford Lehman
Good old Ford Lehmans have raw water cooled oil coolers.
If a raw water oil cooler develops a internal leak wouldn’t it pump the oil out before water would make it into the pan. Raw water pumps generally pump at 5-25psi and eng oil pumps pump at idle more than that let alone at speed. If your oil cooler is below the waterline and has a internal leak then water could make it to the oil pan when the engine is off. If that was the case the engine would flood up to the waterline.