The headliner retainers are something like this:
http://bresco.com/acatalog/-Snapsac--se ... tml#SID=23 - basically a "top-hat" nylon bush with no hole in the top/bottom so the rod sits in it.
But I must stress I don't know if those are the correct (or usable, as they're metric) dimensions. When I was putting mine back in recently I had one missing one, then found it, and measured it before I put it back in the roof. So I can post the dimensions later.