my '91 300d hasnt been to a dealership in at least 10 years. do they replace the trap oxidizer or take it out all together? mine is black and is mounted lower than the one in the picture. ive got 175000 miles. should i take it in?

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1991 300 D 2.5 Turbo, 220k
also in the family:
1981 240 D 185k
1991 350 SD 185k
2006 S 500
2005 SLK 350