I THINK the OEM toilet on that boat was
a SeaLand 751 or 752...not sure when the 751 was replaced by the 752, but it doesn't really matter 'cuz both have been obsolete out of production for at least 20 years...no parts or even a rebuild kit still available.If I'm wrong and it is a W-C, it's prob'ly a "Headmate," which is still in production but is so worn by now that it's unlikely that rebuilding it will do it much good.Otoh, it's highly likely that the toilet isn't even the original any more. So I need to know what it is to know whether it makes more sense to repair it or replace it.That really was a lot of help, wasn't it.

If you can take a couple of photos of the pump (not the bowl...all bowls look alike) and email 'em to to me, I'll be able to tell you what it is.