If you are going to rebuild the lift pump, you may as well get one from a later 240D or 300D, and rebuild it instead. The earlier version that you have has a much less robust main spring, and at 36 or 37 years old, it is likely to fail much sooner than the heavier spring on the later pump. It's also the one part that is not easy to obtain. The Bosch version costs a little more than the MB kit, but it has all of the parts, whereas the MB kit is not really a complete rebuild kit.

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'79 240D