The alternator bracket is held to the case, not the head. From the factory it was 2 studs and then nuts to hold the bracket in place. The usual cause of failure is the use of incorrect nuts along with cheap washers and improper torque. Then add a loose belt or bad alternator bearings and possibly a cheap alternator rebuild with an off balance rotor and the bracket will either crack or break the studs on the case. Next step is the case getting hammered so the bracket cannot mount properly. Some vendors offer a support bracket that can help. Proper fix will be to repair the threads using a heli-coil or welding may even be needed. Good studs P.C. 10.9 and matched nuts/washers. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of john
Sent: Monday, June 1, 2015 8:44 AM
To: vanagon@GERRY.VANAGON.COM
Subject: '84 1.9, lower bolt on alternator mount

I have not had to ask question on this list for months as failures since major work in 2003-2004 have been minimal. After hearing strange noise from belt that does alternator and water pump, I ttok a look at engine compartment and found that bolt that holds alternator bracket to right head had fallen out.  What size bolt is this?

Thank you,

John