This is a genuine GM OEM Duramax Diesel L5P Engine Oil Cooler Assembly.
The Duramax engine oil cooler is not normally a component that goes bad, however, it should be replaced after any catastrophic engine failure or during any performance engine builds.
The factory oil cooler has a stack plate design which makes cleaning any debris out nearly impossible. This is the reason we always recommend replacing the oil cooler. A defective engine oil cooler is also a major source for coolant/oil cross contamination. Check your coolant degas bottle for a layer of oil. If any appears, it is often defective oil cooler.