GoWesty makes this nice kit to beef up the alternator bracket connection:
http://www.gowesty.com/ec_view_details.php?id=4454&category_id=&category_parent_id=

The carriage bolt that comes with the kit seems to be a very low grade.  I
stripped the threads on mine very easily.  And multiple people at thesamba
have had issues as well:
http://www.gowesty.com/ec_view_details.php?id=4454&category_id=&category_parent_id=

(GoWesty was very nice about replacing my bolt but said the hardness was
not an issue even though it was perhaps only class 4.8 or so, since the
bolt "doesn't need to be very tight".  I don't like this perspective.)

Anyways, I think the bracket seems like a very good idea overall (and you
should get one *before* your studs break, not after) but I would recommend
using a different bolt.  Either you can scrap the carriage bolt and use
whatever you already have straight through with a nut, or, the hardest M8
80mm carriage bolts I found were 8.8; fastenal has them.  If anyone finds
10.9 let me know!  I doubt they exist, unfortunately...

When I replaced this not-hard-enough bolt, I replaced the nuts on my
alternator bracket studs with 10.9 versions at the same time since I'm not
sure what was already there was the correct hardness.  Just wanted to
report that if you have some funny wrenches then this can be done without
disturbing the coolant pipe that appears to be in the way.

-Wes