2004 lights can be done. But it would take some careful modifications. If you dont change the wings then you need to modify your original wings to suit the headlights. I'm not sure about the bonnet? I know the 2004 bonnet is slightly different but again with a good bodyshop the old bonnet can be modified to suit. Wiring would be a main issue but not impossible. Have a look at my old e39 540I that I spent alot of money on modifing. I modified the bonnet, bumpers, doors and much more.
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