So I picked up this very clean 1993 W250, 5.9L 12V, all stock, one owner truck, and it is in excellent condition; a few issues need addressing, and one is this chattering sound coming from the bell housing/transmission/back of the engine.

It only happens at idle, with the clutch engaged.

Check out the video below at the link:

https://youtube.com/shorts/JNzZ3rjFPWA?feature=share

I hope I am doing that right.

It is the pilot bearing, clutch, or pressure plate.

But it is similar to the sound the G360 transmission makes in 4th when you are too slow, so I am not sure it isn't the transmission.

Does anyone have any thoughts on this before I start tearing it apart?

Thanks!