First off it had 5 blades. Second of all they were pointed. 3rd, I believe the motor was one of the "smaller" ones, not the big tank motor, and it had a swivel canopy. Finally, it had the "heart" brackets. What set it off as unusual for me was:
1) the 5 square bottom blades, had only seen 4 before 2) blades had both square bottoms AND points, never seen them together 3) Cane was loose weave 4) I BELIEVE it had a swivel canopy
SMCs seem to be quite common in Dairy Queens. The one here has two from the 80s. One is a palm aire type fan with ge vents and the other is a hugger. Both are 42", I believe. There are also two white palm aire types on the other end of the restaurant.