Back then my only choice was the 18 gallon. Probably the FT1894 (port).
There are 24 gallons that might fit in the location. Look at the diagrams and see if they might fit without major modifications.
There are some dimensional differences with the 24 gallon FT2495P (port) and FT2495 (port) as there are also in the FT2495-1 (starboard) and FT2495S Starboard. You gotta decide.
http://www.plastic-mart.com/category...ine-fuel-tanks