'86 Westy

A few months ago I had a loud knock from the rear tire....sounded like a
CV to me.  I was on the road...some of you may remember...and had to drive
300 miles before I could find someone to look at it.  They stated that
they repaired one CV and lubed the rest up.

I drove about 1000 miles on those CV's then parked the van at the bodyshop
for 3.5 months.  When I get it back the clunking is there again.  Now my
regular shop can't hear it and can't detect anything wrong with the CV's.
I bought an entire axel with both CV's installed (brand new) to carry
around with me, just in case, but could it be anything else?  The knocking
increases with wheel RPM and is identical to the noise that the bad CV
caused earlier.

Any help is appreciated,

Gregor