On eBay they have various sizes of filter heads.
It is better to pick what filter you want and then look for a Filter Head with those thread sizes.

Racor Filter Housings are expensive but they have interchangable Filter Elements in different Micron Ratings.

VW Rabbits ( uses a filter with about twice the Volume of the Stock Mercedes filter at 10 Microns and Baldwin makes a filter with a drain at the bottom that will fit it that is somewhere between 2-5 Microns) and of course your Mercedes Filter Housings can be used. But, it is better to decied what Filter and Micron Level of filtration you want and then look for a housing.

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84 300D, 82 Volvo 244Gl Diesel