I used a $20 slide-hammer puller, but that barely got mine out. I had to tap one of them inwards slightly before it would move outward. Dang near wore me out. Might try the $40 one next time. Auto Zone will let you use theirs if you let them hold a cash deposit while you have it.
Somebody told me he used a long steel rod that would barely fit through the diff splines and punched them out from the other side of the housing. Sounds like a good story, but I never tried it.