If the toilet is more than a few years old
It's unlikely that even the same make/model mounting bolt pattern will be an exact match for all the existing holes 'cuz, like most other things, marine toilets are redesigned--either just for style or using improved (or cheaper in some cases) materials. But that's not a major problem...you'll just have to drill a couple new holes, fill and touch up the unused ones.On a boat that size of yours, your toilet is almost certain to be a compact manual. Jabsco is the cheapest, least durable/reliable...the Wilcox Headmate is slightly better quality...both are <$200. Between $200-300 the Groco HF is somewhat better quality...the Raritan PHC--which is the PH II pump on a compact base is--as many owners will attest--the best most durable by far. It's tempting to buy the cheapest, but like most things, you get what you pay for. You'll spend far more repairing and even replacing a cheap toilet every year or two than it'll cost you to buy a good one just once.