L322 Help identify metal scraping sound - 2004 4.4L HSE

I have an 04 4.4L Range Rover HSE with 125k miles. It has been making an intermittent noise for a while, maybe 6 months. I thought for a while it was coming from the engine compartment, but after mounting a gopro in multiple locations, I think I've found where it's loudest/clearest - somewhere near the rear of the transmission. If anyone has ideas as to the cause of the sound, I'd appreciate it. The sound happens when:
- I'm driving - cannot reproduce when stationary
- In 3rd, 4th or 5th gear, usually between 1200 and 2000 rpms while maintaining constant speed
- It stops if I let off the throttle
- When it stops the tach bumps up 100-150 rpm
- Doesn't seem to happen when engine is cold (first three to four minutes)
The transmission shifts fine and the fluid is most likely original.
The sound should be clear in the video, but just in case, the word "sound" flashes on while it's happening.
Any help is appreciated. Video link:
Thanks

That could be the sound of the safe full of money being dragged behind you that may be needed to put it right??
Is there any noise near the bell housing?

Fluid and filter in the auto box needs changing. Have you checked the oil in the rear diff? Also check the UJ's for rust streaks and play.

Mark Piercy said:

That could be the sound of the safe full of money being dragged behind you that may be needed to put it right??
Is there any noise near the bell housing?

Click to expand...

LOL

I just got back from a local transmission shop. I wasn't able to leave it, so they drove it and gave me a prelim diagnosis of torque converter clutch slippage. I have an appt to leave it so they can look at it on the lift, etc.
I didn't find a safe full of money, but maybe when they open things up some change will fall out.
If I decide not to sell it after the full diagnosis, I will certainly change the fluid and filter.

rovermax said:

I just got back from a local transmission shop. I wasn't able to leave it, so they drove it and gave me a prelim diagnosis of torque converter clutch slippage. I have an appt to leave it so they can look at it on the lift, etc.
I didn't find a safe full of money, but maybe when they open things up some change will fall out.
If I decide not to sell it after the full diagnosis, I will certainly change the fluid and filter.

Click to expand...

It does sound ominous unfortunately... I hope also there's some change falls out or gold dust....most likely converter clutch dust.. be prepared for the worst and anything less will be a bonus.