K thanks
I wonder if maybe the consoles work differently, as am playing on the 360.
Over at GameFAQs, a few of us are now farming the bosses and listing the drops, and seeing if we can find patterns - they may be random but some bosses may drop a piece far more often for example.
Ill check some stuff here, and if we find anything conclusive over there, I will post it here at some point too.