The numbers you are talking about are MB's internal chassis designations and they refer to a particular "generation" of car. So the W210 chassis is the E class from 1996 to 2002 (2003 for the station wagon). The W124 is the E class from 1986 to 1995. "W" corresponds to sedan/station wagon and SUV bodies. "R" corresponds to convertible cars.

Your wagon is a W210.

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Jonathan

2011 Mazda2
2000 E320 4Matic Wagon
1994 C280 (retired)