Irg is correct. The trap ox was replaced on my '85 300SD. The catalyst that is in its place looks exactly the same. As far as the 30,000 mile story, I think the dealer was giving you some BS on replacement.

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'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R