I seldom hear of rear bearings going bad on their own. They are pretty
tough. They are pressed in, but are not sealed bearings. They need to be
regreased occasionally, but this is another iffy call. Too much grease and
the seal will rupture. This will cause the second most messy, Vanagon
catastrophy possable. Grease ALL over your new brake shoes, and I do mean
all over them(not that only a little is too much on brake linings). BTDT

So, how much to put in and how do you put it in? A guru at California Import
parts said to only fill the hub 75 percent and leave room for expansion when
hot.  His lips trembled with fear as he spoke.   How do you know the hub is
filled 75 percent when you cannot see the insides? Apparently he had been
there and done that, too. All I can say is to use restraint. It is FUN
pressing in new grease, but like most fun, too much is not a good thing. Got
to go now, bye.

If the hub is swapped with a used one, or a new bearing is pressed into the
old hub, the job is mostly the same; the hub needs to be removed from the
trailing arm,the CV axel needs to be removed, the entire inventory of brake
hardware needs to come off. At this point, the only savings will be for a
new bearing (over the used hub), and the shop work. It is a good idea to
redoo your rear brakes at this time if they are approaching that point. Need
new CV axels?? Talkin' about lots of money here. Better check for loose
wheels, balancing weights, loose CV axels, loose shock absorber( this could
be your problem),or a brake problem. One thing it is not, is a loose
trailing arm. A jack hammer will not loosen the trailing arm, most times.
Only a large bomb will remove it.500 pounds or more. I have to wonder if a 4
wheel alignment is really a 4 wheel alignment in the Vanagon. Nobody seems
able to move the trailing arm. Why pay for it?

 If you folks need Bentley diagrams of this hub I can send some. They show
an exploded view of that area of the Vanagon (with trailing are still
attached in the pictures :>)).