The motor turns clockwise. When putting it back together, try rotating the drive shaft by hand and it will be obvious which way the ears go. Don't worry, even if you get it backwards, it will reverse itself, but it's nice to get it right the first time.
The above comments assume you are installing an impeller that has long vanes sticking straight out. Not all of them do, so not all are self-correcting. Nevertheless, the vanes trail back when the shaft rotates. Think about it--it wouldn't make sense to have them pointing forward. They would "stub their toe".
