Ah, because, as I think Marks DTM pointed out (when I asked on here 'what size is the nut, please, as I've lost it - and will any old nut do?) that it is actually copper, with a stainless helicoil inside, and a bit specialist. With mental images of the wrong nut/metal fusing to the already-barely accessible manifold in time, I decided as it was a one-off extortionate price I'd pay up and look happy. Also tried as asking for a used on on here for beer money/price of postage, but no V6s being broken that week.

Trust me, I'm the
last person to go blindly walking into the dealer and saying 'give me this part, no idea what it is or does, but here is my wallet, good vendor of Automotive Parts. Oh, £7 for a nut... is that a lot?' but as mentioned, was advised on here that it's a bit specialist, so best go genuine Vx. Whether I've done the right or wrong thing, no idea. As I say, by sheer chance I ended up finding the chuffin nut the day of refitting, so all academic.
