Thru Hull
That's definitely a thru-hull, and not damage. $5500 is not a "steal" price for that year and model. I bought my '76 for $6500, but that included a twin axle trailer. It also took some work and money to bring both the trailer and boat up to what I needed (we probably spent about $2500 pretty quickly, $1500 of it adding brakes to the trailer and doing some repairs).You would do well to pay a surveyor, and as RW has said, leave the deal of the deck is soft. You will definitely want the hardware rebedded, as that was done improperly.I'd also recommend (whether you buy that boat or not) that you buy Don Casey's "This Old Boat" book. Reading through repairs that can/should be done on older boats will give you a good idea of what to look for. Then, you can use the book AFTER you buy whatever boat you decide on.