Greg:
When I was sourcing my donor 86 300E 5-spd to swap into my 95 wagon (no, not yet....sitting in driveway), my brother in law (BMW fan....leased a M coupe when it first came out...now owns a 95 M3) mentioned that it was great that the car has a single mass flywheel because the earlier duals were prone to the type of failure you have seen with yours, at least on BMWs. He had read of a few cases of this happening on BMW forums.
Sorry to hear about the big bill.
Good luck.
Brian

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Brian
1995 E320 wagon