Oh, of course, the B4 side skirts.
my ride did not get them standard and that made me sad. I got some off of ebay for ~150 delivered from a wrecker. I had already purchased a 20pack of the 10mm clips on ebay expecting this to be all I needed as that was the only holes in my sill panels (6 per side I think, possiibly 7, will count when I take pics and find the measurements to share). Unfortunately there was a row of clips down each side that I spent quite a while scratching my head how to deal with.
I ended up buying some door clips from auto store and using the only 4 left on the skirts when they were delivered for the ends. I measured and measured and test fitted and put lithium grease on the clip holders and test fitted and produced witness marks and checked again. After quite a bit of stressing I pulled the trigger on the drill and filled my sill panels with holes. Turns out I got the measurements right and after I let the paint dry to rust protect the holes the skirts mounted up really well.
measurements

Of course the silver of the B4 and my special edition was different so they do not colour match quite right. May save up to get them sprayed. The brute that pulled them off at some point in history wrecked the clip retainers on the lh one and I had to epoxy them all back together before fitting. Luckily they still fit up.

still needs a wash...