Any tips or tricks to getting a stuck one off?
I've seen two things that worked:
One was to remove the alternator from the car and put it on the bench with the pulley on top... after removing the protective cap, put PB Blaster (or Kroil, or Liquid Wrench) in the center hub and let it soak in... hopefully that will help break the hub from the armature.
The other was to use an impact gun (making sure the bits are well seated...) - I know that the MetalNerd tools aren't rated for impact gun use, but... desperation sets in after a while...
Yuri
PS: it also doesn't hurt to make sure you're turning things the correct way... the hub is screwed onto the alternator shaft in a normal direction... it's not right-hand thread... often people hold the hub stationary and try to turn the center shaft, which in this case should be turned clockwise...