Does the letter say that the trap oxidizer has to be replaced by another trap oxidizer or that it can/should be replaced by an oxidizer catalyst downstream of the turbo?

What's the date on the letter? Maybe it predates the campaign.

I met a fellow who takes his 85 300D or SD to Smythe European, the MB dealer in San Jose, CA, and he says that they've replaced the trap several times. They've never suggested that it should be replaced or removed.

Sixto
95 S420
87 300SDL