Sooty, if I read you correctly, any W124 6cyl turbo after 1988 or so probably has the newer head?

Hoping to find out more ... Reno

PS: For that tail light, try putting in raw rice with dish detergent and hot water. I once owned a Volvo 740TD that I nicknamed Pepe le Pewe, due to its omnipresent cloud of stinky soot. I would clean out Pepe's tail light every year or so with my rice trick. Worked great!

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Thx/Reno
An American in France
88 300TD 5spd Sportline (lowered factory susp) - totalled by a flying deer
89 Range Rover V8 - the 4wd beast
02 Toyota minivan
05 Peugeot Partner 4x4 Dangel
88 International Harvestor 633SA
--Gone but not forgotten:
1970 250/8 C (sold to buy 450 SLC)
1972 450 SLC (sold after battling wiring harness problems too long)
1971 300 SEL 6.3 (sold after destroying two *very* expensive rear LS diffs)
1986 560 SEL (now my little brother's pride and joy)