Hi Malcolm, great idea! (bigthumb)
Did some research on those rare beasts during the resto of my 3C and found out the following, might be helpful:
There actually two versions with different reflectors and lenses
-Domed lens used on the drummers, lens has Bosch number Bosch 1 305 605 100 (LHD, RHD number unknown)
-Flat lens used on the disc brake models (and probably also on late drummers?), lens has Bosch number Bosch 1 305 605 101 and "H4" imprint (LHD, RHD number unknown).
The domed LHD lens seems available on order at your local Bosch dealer
http://www.bosch-classic.com/en/internet/bosch_classic/produkte/karosserie/streuscheibe_1/streuscheiben___mit_teaser_rechts_3.html. Will try to get a price tag on it during the next days. AFAIK available as new parts as well are chrome bezel (ca. 85 eur) and reflector for the domed lens (ca. 75 eur).
They are rumours that the headlight shell has been in use on firetruck searchlights, but not confirmed so far.
I have never found a flat 1 305 605 101 lens, neither so the matching reflector, rare as a hens teeth I'd think. Bad luck that I missed the lens offered here by Gert.
BTW, the seal for the lens is still available at your local Mercedes dealer, but price tag is north of 100 eur.
That said, you can put me on the list for a shell, a LHD flat lens and a matching reflector. (cheers)
Regards,
Stefan