This isn't specifically a Vanagon problem, but the set up is real similar so
I ask of the list the following question.  Friend of mine has a very nice 71
Westy but the left rear axle nut comes loose every couple thousand miles
despite havingthe cotter pin in there.  He's putting the 300+lbs. of torque
on the nut but to no avail.  The axle is noisy making right turns when the
eight is on that side of the van.

My first guess is a bent stub axle or hub, but if those items are out of
round when spinning, wouldn't that tear up the bearings too?

He has no recollection of driving over anything that would've bent it, and
he's cheap enough to not want to replace a bunch of parts not needed.  The
only other wearing evidence is the castellated nut is grinding a cupped
shaped pattern into the hub.

Thanks for helping

Dimwitted Moose and Flying Squirrel