My rod bearings were shot due to oil starvation, my truck made a diesel like sound that was loudest in the engine oil sump. The engine was aslo louder when cold and got only slightly quieter when it warmed up. I replaced my engine and checked my old engines rods, they all had quite a bit of radial and axial play at the crank. FYI I drove about 50,000 miles on bad rod bearings - gotta love these german engines, they will do anything.
P.S. mine was a "fast" diesel like Knock as each rod was impacting the journals on every stroke, I hope this helps you.