You can literally identify a Hydrostream from a mile away - in looks as well as the way it flies. In 1975, the Viper hull underwent some design changes. I prior to '75, and the Viper II after that. See the Vector model page for more discussion on the design change and the hook. The Viper will seat 4 adults comfortably.
Storage is under the deck and under the front seat.
It is not a roomy boat. The boat handles the rougher water at low speeds surprisingly well. With an inline six for power the Viper will run in the mid to upper 60's. The acceleration is fair with a 115, but you can trim it to the moon and feel very safe and very high. One drawback to the Viper is its ability to handle waves or rough water at speed.