Frank is correct but a little more trivia. The 4 blade fan for the four cylinder Ford came out in 1933 (part #46-8600). Ford designated this fan as the replacement fan 1928-34 and that is the reason so many of them are found on Model A's. If I needed a fan today I would buy one of the reproduction aluminum fans. Be sure to buy a new one from a reputable supplier as some of the early ones had problems.
Charlie Stephens