E body heater box question?

[Bronzedodge]

Friend of mine has his 73 Barracuda completely apart.  He is missing the small metal plate that closes off the hearer core tubes where they pass into the box.  Anyone have a pic or a source?  I'll settle for a measurement of the two holes.  How does it attach - to the core or to the box?

[Bronzedodge]

Anyone? 

Edit:  Looked at a pic - I just need someone with a junk core that has the metal plate intact.