I have the same year but in the 20" model.
My fuel tank just started leaking and I am in the middle of replacing it. By the way after opening the floor up, everything on the inside was still in pristine condition, stringers, transom, bulkheads etc....
I have a Yammy 225 on mine and it is rated for 235 hp. The 225 is a lot for my boat at 20" I would guess on an 18' it would be almost dangerous..........