1965 Ski Twin 33 hp Impeller question

"This is my first experience w

"This is my first experience with boating. I was gifted a 1965 14' MFG from my uncle with this motor on it. Ran decent 2 years ago when I took it out with him and then it has sat for 2 years (long story, but mostly titling and registration hassles). So I am now ready to start getting her back to top working order. I am going to do as much as I can myself so I thought I would start small...I saw that it is a good idea to place the water impeller every year or two. I know this hasn't been done for several years (although with the muffs on it pees okay). I received the service and parts manuals from this site (good stuff). Question I have is, do I just need to order the star shaped impeller pump (OMC part number 378891, Sierra replacement part # 18-3006) or should I get the whole assembly with the housing and plate?

Thanks,
Patrick"

From my past experence I would

From my past experence I would replace the whole water pump and start from a point of where I know what kind of shape it is in. Then there is no wondering about it.

"So then what parts make up th

"So then what parts make up the "whole water pump"? Just the housing, impeller and plate?"