That cat d has been advertised for ages, saw it last year when I was getting idea's and then at the beginning of this year when the wife said "go on then!!"

Can remember reading it and thinking this sounds to good to be true.... which it was when got to the cat d bit
There is a reason that it only has 32k miles..... cuz it was off the road for a long while getting stuck back together!!
As you said xenon can be retro fit, did look into it before buying since was looking at a few without and have a 5 series without and it is crap in the dark. Can be retro, does look like a bit of a pain and from memory was not cheap for the units.
Good luck with the hunt.