Ahh, finally a topic I have some knowledge on ;-)  I kept having belt  after
belt come
loose, and then I figured out that all of the name brand belts come too
large when
ordered stock for my 87 Vanagon.  I finally started asking for one  that fits
around the
power steering assembly, and that one fits my alternator/water pump.   I've
been told
Goodyear Gatorbacks are the way to go.  So far, for the last 4 weeks  at
least, they
have done the trick.  Good luck!
James in Houston
87 Westy (The Phoenix)