Other than Court and Hissing... What else would be in the box?
It is rumoured that Blue may have been mixed in quad as well, even though it was never released.
I can't seem to find it now, but the only evidence I've seen of a possible unreleased Blue quad mix was in a '70s Billboard magazine article that
@steelydave linked a few years ago. The article had a interview with Warner engineer Lee Herschberg, who mentioned remixing the song "Carey" for quad. I suppose it's possible that he kept going and mixed the entire album, but it was never announced in an LP/tape catalog or assigned a record #.