Yes, it most assuredly could be a 1965. To quote from page 73 of McPherson and McCall's amazing "Cadillac Fleetwood Series 75 Limousines" book published in 2009 - "Due to the additional time required to engineer an all-new "D" body, the prestigious Fleetwood Series Seventy-Five models, unlike other members of the Cadillac family, did not receive a re-design for 1965 and retained their exterior styling from the 1964 model year." and on page 74 "The only way to differentiate between a 1964 and 1965 Fleetwood Series Seventy-Five was the three ring white sidewall tires used as original equipment on the 1965 models." The 1966 models got the all-new styling that matched the other Cadillacs of that year and that body shell, with annual cosmetic up-dates, was used through 1970.