Does someone have access to information what the gear ratio of the differential for the 1984 300 Turbodiesel, Vin # WDB AB33AIEA056453 should be?

A second hand diff-assembly installed by a dealer, who claims that all units are the same. They apparently checked with Mercedes and were told that the unit is the same as for my 1985 300 SD Turbodiesel and information on the number of gear teeth of the pinion and the gear wheel are not given.

I have only the Manual for the 1985 SD, which lists in group index 35.1-550/30 F3 the following:

Part number Ratio Number of teeth
123 353 01 85 4.08 23
123 353 02 85 3.92 24
123 353 03 85 3.69 26
123 353 04 85 3.58 27
123 353 05 85 3.46 28
126 356 01 85 3.07 31

This information indicates, that at least on the 85 SD model, different gear ratio's were made.

My milage dropped on the 1984 model from about 26mpg to the present 20mpg. The 1985 300 SD with CA pollution control always gets 23mpg!

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