On the back of these motors, the drive shaft is exposed just a little bit. This shaft runs all the way through the motor and is the same one that the gear will be pressed to. The reason why its this way is so that you can use an arbor press to press the gear on. As mentioned before, heating it helps, but after doing six of these today (no joke
http://www.chiefdelphi.com/forums/sh...66#post1118966) I found that it is easier to do it without the torch and use the free hand to line everything up.
It is also a good idea to cut a piece of sheet metal (~50 thou thickness works well) to use as a spacer while pressing the gear on.