I know of at least one other case were the wrong diff was installed at the factory (long story about the local dealer -- they broke a tooth off the ring gear while messing about with the car and refused to fix it, won the case, too!).

Probably was in there all along.

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!