At 05:15 PM 11/29/2007, Scott Daniel - Shazam wrote...
>That's not a tool you buy by size normally,

Yes, they're available in different sizes, and are measured in mm. 8mm
for Vanagon CV joints. My Audi uses 10mm. The measured size of the bit
is slightly less than the given mm size. I believe the sizes are
actually related to the bolt size they're used on (i.e. an 8mm bolt
would use an 8mm bit, which actually measures about 7.2mm across).

>It's not an allen, and not a torx.

It's an XZN driver, often called a "triple square." They're not hard to
find: http://www.bloomertool.com/XZNbits.html