I know the box you are talking about, it was a custom built 4th order bandpass. Good luck finding one now-a-days, its not going to be easy. Also, the plans for them were held very closely so finding plans isnt going to be an easy task either.

I tend to agree with whoever it was that said go ported. The added difficulty of building that box exactly to specs isnt worth what little gain you will get over a properly built ported.

I didnt knotice if you said it or not, but do you have a cobalt? If not, then finding plans for that box is useless. No other sub will perform nearly as well.