Adding onto Wingtime's good suggestion, why don't you measure the exact dimensions of
the tank "coffin" space in your boat. Doing that will tell you how much room you have to
work with when getting a new tank.
If you don't go with the exact same tank size as was the original tank you will want to be
sure to leave sufficient space between all sides of the coffin space and the tank itself, so
that you can get the new tank into place and get it back out again when that needs to be
done.
When getting a new tank the placement of the tanks "fittings" (filler tube, delivery tube,
interior anti-sloshing baffles, fuel gage cutout, etc) are as important as the shape and
size of the tank itself. These are important details -- so that you don't get an unpleasant
surprise when you start to hookup the new tank.
You also mentioned in your posting that your seat frame had been stolen. Here are two
photos of the stainless steel seat frame that Aquasport originally made for my own 1988
17 ft Aquasport "Osprey" model. I recently replaced the original Igloo brand cooler with
a 65quart Yeti brand cooler. To do that required me to "spread" the rear of the bottom
frame out about an inch from its original frame position. You can see that detail in the
photo of the bottom of the seat's frame. This was the only change needed to the original
frame; and the revised frame allows me to use the exact same deck attachment holes as
were used by the original factory designed seat frame.
