99 E300D noisy Cat? er make that noisy TRAP!

[dieseldiehard]

The cat or trap ozidizer or whatever you like to call it is noisy on the '99 I sold my BIL.
It sounds like a metal on metal (or ceramic on metal?) musical note, actually coming out the tail pipe.
Inside the car its not hardly noticeable. Outside, in back of the car its really loud!
I thought it a mounting bracket gone loose and took it to my experieced mechanic who put it on a lift and pressed on the exhaust pipe from front to back. I believe his diagnosis is correct in that the ceramic matrix has come loose and is rattling in the housing.
I am getting too old to do what I did on a OM603, that was to use some special tools nd a lot of elbow grease to perform what is called a "Trap-Ectomy" with the plugged trap now out the engine runs peachy keen! (plug for peachparts intended)
I guess if I'm lucky I might find a pulled trap from a '99 E300D to swap, no way would I buy a new one.
Anyone ever heard of this happening before?
I am working on a hypothesis as to why this happened - later on, sorry.
DDH