Engine knock, mechanical or combustion noise

[Cansomike]

Anyone else with the 3.0 Duramax hearing a noise around 2000 rpm on light acceleration. Sounds like a rapping noise. Sounds like a mechanical noise but I don’t hear it without load on the engine in park or neutral and if I am accelerating it sounds rather normal for a diesel. Also, if I approach 2000 rpm at light throttle and then accelerate a little harder I don’t hear it. I’m thinking it is just combustion noise and just wondering if anyone else has it. 

[OlyMike]

I hear it too during 1/4 pedal acceleration until the transmission shifts down, like loud lifter noise. I can also hear another weird sound at low RPM acceleration, kind of like being in too high of a gear when driving a manual transmission.

[Mike Borowski]

I have what sounds similar to this but I have the 2.7L.  Mine is more like a rattle or rough idle when accelerating around 1500-2000rpm.