First, find the tank...
Then follow the hoses that are connected to it to their ultimate destinations. There should be 1.5" ID hose at or on the top of the tank coming from the head...another 1.5" hose coming out of the tank at the bottom that goes up to the pumpout fitting on deck (which is the one you're looking for)...and a smaller diameter hose (which is the vent) coming off the top that may also go to the deck or exit the hull just below the toe rail. On a Hunter, it will not end in a rail stanchion as it does on a Catalina.That's what SHOULD be there. 1984 was right on the "cusp" when it came to factory installed holding tanks...some boats had 'em, a lot didn't...tanks were added later by owners as states passed laws requiring 'em, and some owners resisted putting new holes in their boats for things like deck fittings and vent thru-hulls...so they didn't. They made it necessary to pump out the tank by opening a cleanout on the top of the tank and sticking the dockside pumpout down a hatch into the tank (which is a VERY bad idea because pumpouts have a nasty tendency to "burp" and spit up...something you DON'T want to happen anywhere INside your boat!). So the only way to find out how YOUR head and holding tank are installed, and where all the parts are, is to trace all the plumbing to see where it goes. You might also want to spend some time browsing the articles in the Head Mistress forum reference library (on the forum homepage) to learn how to maintain your system and keep your boat odor-free.