My guess (and it is only a guess, I've never taken apart an MB tranny) is a part of the shell on a Torrington bearing (flat bearing with radial rollers) -- too small to be anything else with rivets or holes. If it is, you are going to eat up the internals pretty fast, although it will shift just fine.

245,000, you are getting close to the end of the life of the automatic. Rebuild now will be simple, replace the clutches/bands, new bearings, sliprings, and seals, and off you go. If you wait too long, everything gets munched and it gets REALLY expensive.

I'd go talk to a tranny shop before I paniced, but you may want to plan on work fairly soon.

peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!