I know this thread is pretty old but i was figuring out th eoptions on my car (1989 300e and 1987 300e) and I believe 446 is codes 441 and 442 (443 refers to 440 and 441) so i think 446 is 441 (elec. adj. sterring column) and 442 (airbag in sterring wheel) which i think was pretty much standard in every w124 sedan.

__________________
89 300E Pearl Grey Metallic
7 Spoke 16" staggered wheels (SLK)
215/55/16 Hankook Ventus HRII H405 tires
Euro Headlights
Smoked Corners
Smoked red/clear tail lights

1987 300e Black Metallic (mom's car)
8 hole 15" wheels (C Class)
Clear Corners
Red/Smoked tail lights