I remember that kit well--built it when it first came out when I was in high school. The kit tank is an early M4A1 with direct vision slots and three piece transmission cover, but has the later M34A1 gun shield, so it would have to be a rebuild, either a modernized tank or a hull that has been mated with a turret salvaged from another, later, tank (such vehicles do turn up quite late in the war, though the M3 style suspension was rare). The tracks are a problem, since Monogram centered the track block connectors on each block instead of in between them, so they don't actually connect anything.
"Eternity" appears to have a slightly later M4A1 tank hull with the periscopes replacing the vision slots, the original M34 mantlet, and the original M3 suspension, and based on the camouflage, would have been photographed in Sicily, too early for the late turret configuration in the kit.