Baseado na minha memória do filme e esses trechos de "A Arte de Star Wars: O Último Jedi" eu estou inclinado a argumentar que é, na verdade, um T-65 X-Wing Starfighter, e não o atualizado Modelo T-70. Minha filha acabou de receber o livro como presente, então vou ter que dar uma olhada quando chegar em casa para verificar.
"In February 2013, Doug Chiang painted Luke Skywalker's X-wing starfighter sunk beneath a tropical turquoise sea for The Force Awakens development," the book reads. "The idea would finally bear fruit in July 2014, when Kevin Jenkins returned to the concept in early pitch art. "
"'I wanted to tell a slightly different story: As Rey finds Luke on the island, maybe she stumbles into these caves and upon the X-wing, rather than seeing it from a distance,' Jenkins says," the books reads. "In 2014, he wrote, 'Rey explores the island, trying to understand Luke's self-imposed exile from the universe. She comes across a cave, sunk at high tide within the base of the island. Here she discovers Luke's scuttled T-65 X-wing, rusted and rotting away in the water. It was set alight before it sank. It shows Luke's commitment to his exile, as he destroyed his only means of leaving the planet.' In the end Rian Johnson chose designs more similar to Chiang's initial painting of the sunken starfighter just off the coast of the island." 
Outra página sobre a cabana de Luke em Ahch-To afirma que
"Door made from salvaged foil of Luke’s T-65 X-wing." 
A imagem mostra claramente o padrão listrado vermelho da asa do T-65 original de Luke.