So, there are clearly two versions of the Mk2 non-HID headlamps. One with the wire clip bulb fitting and the other with the bayonet system (presumably appearing later). Once Rimmer's site is back in action, it will be interesting to see if that difference is apparent in the part numbers for mK2 headlamps fitted through the Mk2 era.
EDIT: Growing old I guess. It was apparent as far back as 2015 that some Mk2s have wire clip bulb fittings. This thread reports a 2005 model with them (Post 10):
https://www.the75andztclub.co.uk/for...d.php?t=207733
My 2004 1.8T has bayonet fittings, so it's unlikely to be VIN related.
TC