Yes, the handles do differ from year to year. Generally speaking, 47-50 handles interchange...that is...you can mount the whole unit from a 47 vent window on to a 49 vent window frame...but the buttons and arms to look different. 51-5 units are different than 47-50 units. Whats shown in the auction are 51 units.
47-50 units have wider channels...the part that mounts to the frame...than 51-5 units.