lizem, being a purist I opted for the genuine MB assembly when our 1998 E320 had loose elements in the driver's side catalytic converter assembly. As I recall, there were actually 2 small catalytic converters in the assembly. Online the price for a new catalytic converter is over $500, so I would be skeptical of a muffler shop's quote of $250. I always feel that "typically you get what you pay for."

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Fred Hoelzle