D6B Rod, rocker arm, or wrist pin noise?

I thought I could hear a deep low pitched knock as you walked back behind the tractor the first time around, but later I didn't notice it and when you shut it down, I didn't hear a piston slapping the head. So unless you are hearing something else, I think you're still good. Doesn't mean it won't let go tomorrow, I just don't hear it now.

What does the oil pressure do at idle?

I runs about 10 to 12 lbs at idle warm. What I hear sounds like a rocker arm to me. I haven't checks valve adjustment yet, but getting ready to pull the cover and do that.

Several years ago my D7 17A had a knocking noise that turned out to be a bad injector pump. Not sure if the fuel injector system on you D6B is similar to a D7 17A but if it is might purchase a new injector pump and try it in each position to see if it changes the noise.