2021 duramax silverado 43k miles. Tonight as I got off freeway my 21 deisel all of a sudden started to sound like an 85 deisel. Really loud and out of ordinary. I have absolutely no lights on dash saying anything is wrong. Oil pressure is good, temps are good and battery is good. Temp does fluctuate up a bit from time to time but all seems good. Seems to still have power on acceleration. This is my first deisel so I'm lost... any help would be appreciated

 

Well I drove to work this am and not one engine or other light on dash to show a warning. All pressures are good and truck ran normal. But the sound coming from under the truck is horrible. Maybe I'm just not use to a diesel, but it has been colder than this and no noise at all. Not sure what to do at this point.