With regards to the 2 Many DJ CD's, apart from Volume 2, the rest are unofficial (i.e. bootlegs), and some of them aren't even 2 Many DJ's.
So, if you want to buy the CD, be wary of this fact, and download from a file-sharing application, or buy the unofficial one as cheaply as you can! Even better, if you know someone who already has one, ask them for a copy!
With regards to the catalogue number question, Pacific/Cubik/The Only Rhyme That Bytes '98/'99 mixes were released with the 'ZTT nn' prefix and not 'ZANG nn' prefix (including promos), which is what I meant when I said that 'ZANG 98T' doesn't exist.
As far as I know, a Grooverider remix of Cubik also doesn't exist commercially, just Pacific, but as I said, I'm open to be proved wrong!