The month of production appears on the plate on the door jamb of every MB I have seen...so ask the seller what it says. Chances are good that a 1990 model year car was made before 2/90 as they probably began production in the early of 89 for the 90 MY (my 98 was made in July '97, as an example).

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz