I am currently on my 3rd 406, this one being a D8 1.9td GLX, which i work as a taxi. Currently on 190,000 miles and still going strong, apart from the usual!
With regards to the self-denting doors, which pinch a bolthead (i think) if the door suddenly opens further than it should, well recently on a windy day, I got it both sides

Do the rear lights and boot from the d9 fit the d8 without major problems, or are the rear quaters different? I rather like the smooth look!
Love this forum, loads of good advice and banter, wish I had found it yonks ago!