Technically you may have a problem with the D2a light assembly. The light assembly is fed by one multi pin plug, 9 or 11 pin depending on market, if memory is correct (or maybe 7 or 9)– it feeds High/Low, parkers and indicators and has 2 earth feeds. The extra two pins that were never used in AUS are, ironically, for the Electric Headlight Height Adjustment Motor. The issue will be that the assembly has an internal loom and the HID kits mentioned are meant to be plug and play - the plug and play duel pin plug is inside the light assembly.
So you would need to either
* mount the ballast box internally (not really possible),
* splice the wire (balast to globe) into the factory loom (not recommended at all with the high voltage that HIDs use) or
* cut an access hole in the rear of the light to allow the plugs out and back in, (which is going to cause a problem with water sealing)
With our D2a I fitted good quality Halogens (Osram) and sliced relays for High and Low into the loom just behind the lights (there’s quite a voltage drop through the factory loom), this gave a remarkable improvement in light output, not quite as good as the HIDs in the rangie but close.

