Actually I think the original equipment was the triple square setup but most
of the Vanagons I have worked on actually have allen bolts.  Usually CV boot
kits come with these fasteners and mechs replace the triple square with the
allens.  The thing that I would stress about this proceedure is to have a
pick or a very small screw driver handy and clean out the fasteners so that
your tool and bottom out in the hole.  Before I started doing this
methodically I stripped out many a bolt (not a pleasant experience).  Since I
started doing this I think only one has stripped.
Have fun and try not to get dirty.  :)
Ken Wilford
Van-Again
John 3:16