[Roadsters] Alternator Mounting Bolt Sheared

[RWM]

Preparing to take the car out this morning, I heard a rattle and noticed 
the lower alternator mounting bolt was loose.  On inspection, found it 
had sheared at the top thread, presumably rest of threaded portion 
remains in the U20 block.

This may be my incentive to remove the alternator and re-mount it on the 
passenger side, but what am I looking at to try and extract that bolt?

- Bob Mann, '68 2000 Solex