On my MD2020 D, the outside diameter of the air inlet pipe to which the filter has to be attached, is 66mm. Your 2030 will most likely be either the same or larger. However, I've just looked at the Keypart website, and they list the identical part number (3580509R) for both the MD2020 D engine on my boat and your MD2030, and that would suggest that your air inlet pipe is the same size as that on my engine.