Bosch rebuilt starters are being shipped with a new bushing for the 
bell-housing end.  Here's a tip the dealer gave me for getting the 
old bushing out.  It worked wonderfully.

Thread a tap into the old bushing.  When the tap hits bottom, keep 
turning and it will back the bushing out just like cake.  If you're 
really cool you use an air-ratchet on the tap and just B-R-R-R-R-UP 
it out :)

-dan