Well, I figured it out...but it took a while and Whale does not make it easy.
So here it is:
What was called the Henderson MK V Bilge pump
when Henderson made it, is now called the Whale MK V Sanitation
Pump. This is a different pump than the Whale MK V Bilge Pump
which I had ordered thinking that it was the Henderson MK V with the Whale name. Both pump at the same 17.5 Gal rate, but the "Sanitation Pump" is white. It is the direct fit replacement, so I won't have to change a thing except for the pump itself.
It's a boat so it is never easy...but what would I do with my spare time without her? And she solves my disposable income
issues since, because of her, I have none.