I think you probably mean 300E or 300TE, pre-1994 would be letter in the rear. It's actually ASR - which stands for accelleration skid control or anti-slip regulation. I think it's a German acronym that doesn't translate perfectly. It was a fairly rare 124 option in the early 90s. Any car so equipped would have a snow chain button and an ASR warning light under the instruments. There's nothing in the VIN but enter the VIN on the Russian club web site and look for option code 471. Try a search above for "ASR" or "ASR light" -it has a colorful track record.

http://old.mbclub.ru/mb/vin/?lng=eng