I searching Garrett's website and catalog for that damn special turbine housing so that I could get PSI (local shop) to order it direct from Garrett. Still never found the part #, but what I did find is a great price on the housing at a place in Kirkland, Washington called
wideopentuning.com. This is the lowest I have seen the housing anywhere, only $265 + $20 shipping to me(Oregon)...
They also sell everything ATP but for cheaper if anyone needs flanges or whatnot!