Waste Deck Fill on 2004 265 CR

[Waste Deck Fill on 2004 265 CR]

I have a 2004 265 cruiser and dropped my waste fill cap in the river. I am having trouble finding the proper sized replacement. Any ideas?

 

I can replace the entire fill unit, but the existing one seems really tough to remove from the hull. Is there a trick to loosen it? (Yes, I did remove the screws 1st!)

 

Thanks, John

[Maceraror?]

How can I tell if i have a macerator? There is a fuse switch on the electrical panel.