Good info I found.
I mis-spoke. My 85 CA 300D did not have the "trap oxidizer" when I bought it. It had the factory replacement "oxidation catalyst" (PN A 126 490 34 14) that fits in the same place. Easy to identify since the later has a shiny sheet-metal heat shield instead of bare cast iron. Not on the car now since I kept the federal manifolds that came on my earlier used engine. I will hang onto the catalyst, manifolds, and turbo in case EPA or CA emissions rules change and I must put my car back to 1985 factory setup. I would prefer not since the new catalyst is still upstream of the turbo and still threatens it with ceramic debris.