Hey Tristan, Good to see you working on some green. Does your 45 have the Herc flathead engine? If so it is a 1957 or earlier, the 45 came out I believe in 1954; and used the Herc engine until JD started using it's own engines in combines, which was the 1958 model year.
Does it have an actual serial # plate, if not it may still be stamped on the frame.
Good luck, Brad