text: The D2-55A when they first came out used to use the 3581621 filters which were the same filters that the earlier MD22 series engines used.
  Fairly quickly Volvo Penta came out with a D2-55A filter which is a 3840525. This is the filter that all of the D255A, B,C, Ds now use.
  The 3581621 has now been made obsolete and been replaced by a 21549544. This filter is used on very few engines, but it would probably be OK to use on your D2-55A, but Volvo Penta would say you should use the 3840525.
  Hope this helps.