I can't help with this exact question, but I do know the answer if you were to ask about fitting a 300D manual transmission in a 190D, which should be very similar.

I have a W201 190D. The manual transmission failed, and the replacement that was installed (by a Mercedes dealership) has a part number that starts with 124 instead of 201. This implies that the original W201 transmission may have been superceded by a model that was designed for a W124 car, and it also implies that some 124 transmissions will fit in 201 cars.

As a result, I now have a 124 transmission in a 201. Assuming that the transmissions aren't radically different for the gasoline versions of these cars, then it seems likely that the W124 300E transmission would fit in the W201 190E.

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1989 250TD Wagon 5-speed, 160,000mi ::: Dark gray metallic / black cloth
1984 190D-2.2 5-speed, 287,000mi ::: Silver-blue metallic / black MB-tex ::: SOLD