Welcome to iBoats . . .
Based on a quick Google search there is not much out there for guidance. I see from web pictures that the boat has a carpeted floor. So, it would be a fair guess that there is not a hatch or anything that can be easily removed to access the fuel tank.
Usually, there is a small hatch, either in the ski locker or elsewhere for viewing the manufacturer's label of the fuel tank. Otherwise, you can often see the fuel tank by looking forward from the engine compartment.
Since the boat is 33 years old, the exact fuel tank may not be available, but often tanks for older boats are custom made, using the original tank as the 'spec'. BTDT on a previous boat of mine.
I'm assuming the tank is leaking? Pulling the old tank out will probably open up a can of worms in terms of other issues to be found, but probably has to be done to make the boat safe to use.