Believe it or not, that part number is genuine and is the diesel cruise loom. BUT as far as I can tell, it was never made available - as you very rightly say, the cruise loom is bundled with the main loom (one of several for various variants of our cars).
I have always wanted to locate a complete (or at least part!) of a main wiring loom with cruise and heated seats to retrofit these items - with the aim to unpick it, and fit the resulting subloom to my car.
It may well be that making up a complete new loom from scratch is actually easier!
