What is this Rattle in the front of my Cat engine?

IT is a Cat c12. Cat did a complete rebuild 250k miles ago. I have had the truck for a year and its always had this rattle. I have heard one or 2 other trucks with cat motors on site with the same rattle. My mechanic who owns a large fleet, half of which are cat engine equipped told me it will probably make that noise for the rest of its life its just wear. Anyhow, I have OCD and it bugs the crap out of me.
The ratte sounds like a bad tensioner but its not that. I removed the belt and ran the truck. Only thing spinning was the crank pulley and balancer, Still makes the sound. Seems to be coming from the crank area. It is definitely coming from the front of the motor and not the radiator. Noise is too low on motor to be coming from the idler gear but who knows. ONLY makes the sound on a warmed up engine and the sound goes away if you bump the rpms up. No noise when cold so I find it hard to believe its the balancer.
Heres video. The first part is with the noise on a warm engine. second part of video is a cold engine and no noise. Your thoughts?

 

cant hear it in the cab my friend. just if I get out and walk in front of my truck. I have the most INSANE OCD you could possibly imagine. I guess I should post this thread on OCD forums lol

 

It’s probably gear lash. Although it does not do it on a cold engine. I removed the belts. Still there. A very large and reputable cat dealer locally did the complete overhaul. I assume they did everything to spec. It was 250k miles ago and done about 8 years ago.

C12 an ok motor for local work bro. Have a few friends running them. Mine is tuned to over 500hp. She pulls with the big boys.

I’m pretty sure the dampener is original. Like you, I’m scratching my head if that could make the noise but you would think it would make the noise hot or cold. There is no play in it

Yes that’s low idle. Nothing is loose bro. I had motor mounts tightened. Everything is solid. Sounds just like a tensioner rattle

 

I’m thinking it might be damper. I read somewhere it has fluid in it. The damper has no play though