Strange Noise - but...

[Skeen]

I have a noise coming from the middle right side of my car that sounds like a bearing going out and grinding/etc. There's also a metallic rattle.

 

Here's the strange part: I've replaced the rear differential with a another diff I know wasn't making any noise, noise still there but slightly better. I replaced the center diff (including transfer gears) on my 5MT with parts out of a low mileage transmission that I knew was quiet, noise still there but much better (previously unbearable). Thinking that I narrowed it down to the driveshaft carrier bearing: I swapped the drive shaft with another low mileage donor, noise still there.

 

The car has 3 brand new wheel bearings, and the fourth came off of a low mileage car and is up front on the passenger side. The sound isn't coming from there... I think. It's almost as if the noise originates right behind the passenger seat. I have triple checked that the exhaust and driveshaft aren't making any contact.

 

Strangest mechanical issue I have ever dealt with on a Subaru. Next step will be replacing the transmission as a whole, but I'm trying to think what else it could be before I commit to that.

Edited August 27, 2019 by Skeen
clarity

[Brighton96]

I'd see if you can borrow a gopro and mount it under the car and then film driving around under the circumstances that it makes the noise. Then go back and watch the video and see if you can see or hear it happen.

[abracadabra89.wk]

I have a similar noise but I believe I’ve narrowed it down to the right hand front caliper. The guide pins allow it to slightly move and it squeaks.