Palangi-

Thanks very much for your help! Your information is correct and correlates with information I received from Mercedes customer assistance, using the vin #.
What's interesting is, they don't seem to have the information in the same detail as the manual I have, listing the number of teeth for the ring gears.

I was told that the ratio is 3.07 :1 for the 1984 Turbo diesel and for the 1985 300 SD the gear ratio is 2.88 :1.

My 85 manual does not seem to have the ratio they quoted, but that's not my concern now.

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1985 300SD Turbodiesel - wife's car
1985 300TD - my car