Bob and Higgs are right...
A toilet that old isn't worth the cost to repair it...even if you could get repair parts for it, which is unlikely because, IF your toilet is still original--which it could be, 'cuz the toilets made then were far more durable than most made today--it's most likely a Mansfield 751, which was discontinued some 25 years ago...no parts or even repair kits have been available for more than 10 years. However, it's more likely that it's been replaced sometime in the last 30 years...so if you'll email or post a photo of it that shows a good view of the pump (not the bowl...all bowls look alike), I can identify it for you and tell you whether it's worth putting any money into. 'Cuz Bob and Higgs are also right that it costs almost as much--or even more, depending on what it needs--to repair a small compact toilet than it does to replace it.As for what Catalina is using now...Jabsco. You don't want one. If the boat doesn't have a holding tank, you'll need one...and you may or may not need to replace the hoses. If you do need a tank AND a toilet, it may make more sense on a boat that size to go with a self-contained system...iow, a "portapotty" that isn't portable, but permanently installed and fitted for pumpout. We can pursue that in more detail after we know what you have and how old it is/what condition it's in.Meanwhile, you might want to check out the link below...it'll take you to a comprehensive "marine sanitation system 101" manual.