90 CD torque converter failure?

[lefthooker]

Cruising on the motorway the other night at a steady 65/70 mph, my car gave a sudden jolt followed by a brief but loud screeching sound. Instinctively I eased off the throttle immediately and took it steady to the next junction which fortunately was about a mile away.
On leaving the motorway I continued to drive it for a mile or two (with some unhealthy noises coming from it) until I could find somewhere suitable to park up.

I've subsequently jacked the front end up checked it over. There is a constant hollow metallic rattle/grinding sound coming from the vicinity of the torque converter/ bellhousing area with the engine running, sound does not alter whether in drive or neutral.

So the question is, from the description given, is it likely that the torque converter has failed or in the process of failing?

For reference, the gearbox is a type 087, part number 087 300 036 E, item 2 here:

http://audi.7zap.com/en/rdw/

Any input would be much appreciated, thanks.