The only clear indicators made by MB that I have seen in the US are the ones on 95 E320/420s, and they have an orange reflector "stripe" at the back. I believe that Hella makes some clear ones, and they are an MB OEM supplier, so if you can find them, the quality should be right up there. Maybe some of the European members know if MB has clear indicators available in Europe.
2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)
Click to see 87 300E