Have you tried your local Renault parts dept? Plenty of old Renaults still around in France so maybe still available. You might have to be a bit assertive tho. Make them make some phone calls. I did actually locate a headlamp on this French website but its only of use to you if you can figure out the site for yourself.
The RTMR has a Yahoo group here which is open to non-members. There are always people either looking for parts or advertising where they know parts can be found.
You might consider joining the RTMR, though, loads of help and advice (I admit I'm biased - I'm secretary and rally co-ordinator ), 4 rallies a year and a quarterly magazine - all for £9 a year.
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.
Topic: 1985 Renault Trafic holdsworth
), 4 rallies a year and a quarterly magazine - all for £9 a year. 
