Good used rear end differential as shown. This one looks like it was worked on or replaced. If your rear end is howling, replacing it with a good used unit is the best way to do it. These rear ends can be very expensive to overhaul PROPERLY.
Product Details
If you have a 123 240D or 300D non-turbo and desire better fuel mileage for freeway driving, then I recommend you replace your rear end with this lower-ratio unit. I have done this on a number of 240D four-speed manual cars, and it makes a great conversion. On the 240D automatic, you will lose low-end acceleration on takeoff - you will have to decide what you need most. When placing this in a 300D non-turbo, adjusting the shift points will not significantly impact power. You will notice a lower engine speed at 70 mph, which is a notable benefit.
Note - no leaks out of the front pinion seal.

