reviving old seacraft (propeller question)

[bitsamonkey]

Thanks for your help on the prop. Now to the next issue...
The boat has a HUGE tank that takes up the entire console, including the forward seat portion of it. Have you ever seen a seacraft with an external tank like this? Or do you think someone abandoned a bad tank under the deck? It is a '69 and I believe that's the first year for these. It does not have any storage cutouts along the under gunnel liner like all the boats I've seen in your pictures. In any case I'd like to have an under deck tank and a smaller console.