Your sender should be under a round access plate either behind your console or under the console. It will look like a disk screwed to the tank with wires attached. Be careful when you remove the sender, because the screws are just threaded into the aluminum tank and are easy to strip.
Given that the boat is 33 years old, I’d inspect the tank while I was at it, especially if you smell fuel when the access is off. If the tank is original, it’s living on borrowed time.
