Can a modernized Elco PT boat mount Harpoon?
Short answerYes, but it should not: Naval Strike Missile or newer weapons would be more appropriate.
NotesA modernised Elco-sized PT boat could carry Harpoon. The preference is nevertheless for Naval Strike Missile because Harpoon is regarded as old technology. Other missile projects are also considered promising, though they are unnamed and are not yet fully in service at the time of the answer.