I know it’s just a pick up but with all the problems I have had with this engine noise Maby this will help others out . My truck is a 2017 gmc with the 5.3 after I gout it I got a cold exhaust leak would make some noise on start up then go away . Then it developed a hard shift from 1st to 2nd when cold and only one time . Then it developed a knocking sound when cold like it had a diesel and you could hear the injectors rattling this would happen when cold for a few miles then go away but if you let it idle for a few min it would come back and then go away after a few miles . Also the fuel mileage sucked if you sat in traffic the fumes got worse . Finally I bought new manifolds and gaskets I only had 1 broken bolt but the last 2 ports were leaking . Fired it up with the leak fixed and no injector knocking and shift problem is gone the exhaust leak caused it to over fuel go figure hope this helps others