I took a listen with a stethoscope. With the knocking present, I took a listen throughout the oil pan and bottom of the motor. Couldnt pick up the knock at all. From the top, I could hear it better. Seemed to be most audible on the driver side top of the motor. Does anyone know if a cracked manifold produces a KNOCK sound until warm? I full well know what the TICK sound is, because I had a broken bolt on the passenger side.
I posted in the linked thread, I have the identical sound and have tried various ways to get rid of it, nothing works. It only shows up on a cold start on a cold day. Cold start on a hot summer day like today, it's either not there or very very minor. So it is definitely temperature related.
I heavily doubt it is a worn bearing issue, mine has done it for 4 years now and since the day I bought it new. It now has 55,000 miles on it which is a long time to be running with "worn bearings". UOA reports show no signs of danger whatsoever, copper is slightly higher vs other 5.7 hemis but that's because of the cooling system in our trucks that other 5.7s like the charger/challenger don't have. Other wear materials in my engine like iron and aluminum are better than average.
Once I noticed the noise and looked for it, it hasn't gotten worse or "progressed" in volume or intensity. It only varies based on outside temps and engine load, so this problem isn't getting worse with time.
The key things that identify this issue vs other known hemi noise issues:
- only happens when cold (both outside temp and engine temp)
- becomes signifcantly louder when a load is placed on the engine (drive/reverse)
- gradually disappears when truck warms up and does not occur on a hot start, my truck is extremely quiet and buttery smooth at hot temps.
The fact that it doesn't show up when hot rules out lifter tick/failure.
The fact that it gets louder/softer depending on load rules out exhaust issues (manifold/bolts).
This is also sounds like a "knock" and not a "tick" like exhaust or lifters. My best guess after digging around for quite a bit, is that it is indeed piston slap.
What oil are you running? Weight + brand?
And secondly, do you use MDS or disable it?
Pressing them to provide me rental car coverage since they did away with loaners during the pandemic. Needless to say, I hope 5.7 eTorque isn't on backorder and we can get some resolution in a couple weeks at most. ...then I can think about selling it. Too many issues (recalls, software glitches, window leaks, etc). 
