Yes, that long bolt has an Allen type socket head.  I think it is 8 mm.
You need at least 15 inches of extensions and a rachet while you reach
above the starter and trans.  The bolt is captive when the starter is
in place; remove it completely after you drop the starter.
   The AT starter shaft is completely supported by the starter
housing; no bushing involved.

Disconnect the neg battery terminal before starting.   :-)

have fun,
Larry A.

On Thu, Nov 4, 2010 at 3:42 PM, Michael Sullivan <sandwichhead@gmail.com> wrote:
> Is the top bolt holding the starter in an allen bolt? �Anyone know what
> size? �BTW-Picking uo a new starter later and want to get this one out...do
> I need the starter bushing? �Hate to drive back over there later. �Thanks.
> Michael in San Antonio
> 91GL Weekender AT 2.1L 'Gringo'
>