What's the sound I'm hearing?

[MRB18]

When backing up, no matter if the clutch is at the clutch point, or pressed in past it a little bit so it's riding the clutch, I hear this loud knocking/metal banging/chatter sound that doesn't sound normal. I noticed that the more gas I give it when letting off the clutch, the less it makes the noise and backs up normal.

Also, the car is a 2.2l '98 legacy and I have another that is a 2.5l '98 outback with an excellent transmission.. I was wondering if the outback transmission is compatible with the 2.2l motor so I could swap it over if it needs to be done.

[csweston]

Not sure what the noise is. Im sure others will chime in. As for the transmission in the 98 OB it will bolt right in to the 2.2 Legacy.

[Baddog]

Any chance it could be the throw out bearing?