The gears should work from the tiller to the thrower unless the height of the gears is different. There are 2 styles of gears for both the throwers and tillers. The tiller gear will really spin the thrower though.
Measure blade tip to blade tip, that will tell the tale.
It should have a metal tag riveted on it as well.
Post a pic as well if you can as all decks are not created equal, even if they are the same size.