Problem solved! Here's a final update: When we last discussed this, two
very experienced list members weighed in on it.  Scott suspected either
the wheel bearings or the transmission, and Daryl suspected nothing but
wheel bearings. Their difference was simply a matter of "a pinion".

It turned out it was a bad wheel bearing. I restricted driving the van
to short trips, and eventually the noise got worse enough that it became
easy to find. It was the new left rear inside bearing, and it had a
cracked race. 
Better yet, the shop replaced all 4 under warranty, which was awesome.
I'm happy it wasn't the transmission, but when it does go Daryl & Scott
will certainly get my business. Thanks for all of the advice guys (and
to the others who commented), it was very much appreciated. Desert trip
this weekend!

Walter

-----Original Message-----
From: aatransaxle [mailto:daryl@aatransaxle.com] 
Sent: Thursday, January 15, 2009 9:40 AM
To: Walter Houle
Subject: Re: Re: Transmission Noise ?

Wheel bearing ..period...Just because they were repl doesn't mean they
are 
good. Esp considering they started being noisy just after replacing
them...
Wheel bearings..period.

-----Original Message-----
From: Scott Daniel - Turbovans [mailto:scottdaniel@turbovans.com] 
Sent: Wednesday, January 14, 2009 9:27 PM
To: Walter Houle; vanagon@GERRY.VANAGON.COM
Subject: Re: Re: Transmission Noise ?

Well !
How kind, considerate, and helpful that you've answered my questions so 
thoroughly - what a pleasure !

ok.......a cyclic donning......cyclic any time the rear wheels are
turning.
Does the frequency of the cyclic sound speed up with more road speed ? -

probably I'd guess.

my hunch is towards either rear wheel bearings or the Ring and Pinion,
or 
the side bearings .........the large side bearings that support the ring

gear......or ring gear holder.

I would tend to lean away from thinking it's the rear wheel bearings if
both 
sides have been done, and both sides checked.
Seems unlikely there would be a problem with both sides. I suppose
faulty 
new parts or workmanship is possible.  Fwiw......I've never had a
problem 
with them after doing them.........but I also wonder if the quality of
parts 
has gone down from say, 8 years ago.

another thing making me lean toward the transmission is the high miles
on 
it. And worn side bearings in the ring and pinion area matches the
symptom.
Be nice if you had another trans to try.

oh.............all right.........here is a listening test you can do in 
flight.  Have someone else drive so it's doing the noise.........and put

your ear right on the shift knob......
or your listening stick.
If the cyclic droning sound is there at the shift knob, from sounds
coming 
up the shift linkage..........again, my vote is 'trans' .....especially
the 
side bearings at the R & P......or the R & P gears.

there's no way you can reach much to listen to while driving with the
engine 
cover removed.....plus engine noise and road noise would be a lot.
I suppose you could get a thin listening stick onto the top of the 
trans..........that might work.

if it does it at say 40 mph 'in the air' .......jacked up and 
running.........if it makes the noise under those circumstances, you
should 
be able to isolate it.
it's really fun to put your listening stick on various things......
and a baseball bat, if that's what you used, is too big.  You can hear 
injectors clicking, listen to the alternator bearings, listen to the 
distributor turning......
listen to the fuel pump internally ...........anything you can think of
that 
moves or flows......you can listen to it very nicely this way.  I happen
to 
have some long slender teak wooden rods.........they work great.  I'd
think 
the denser the wood the better it might be at transmitting noises.

And ..........there are some things that you just can not identify until

taking them apart.
I'm leaning toward the trans...........and if it'll do it running at 40
mph 
or even faster in the air..........you should be able to find it.
try that listening to the shift linkage going down the road too.
The shift linkage makes a great noise transmitter for transmission
noises 
sometimes.
Awaiting your next report.
Tanks again for the comprehensive answers.........Sometimes it feels
like .I 
don't see all that much intelligent expression and cooperation on
internet 
groups .......
some for sure, but it's not like it's 'the normal thing' .   Like you 
know...........someone that interacts and writes with enough information
for 
the other party or members to actually understand them easily !   Soooo
nice 
when that happens. Pleasure to read your intelligent and well-written 
responses.
   I'm thinking trans right now.
Scott

----- Original Message ----- 
From: "Walter Houle" <whoule@ECSCONTROLS.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Wednesday, January 14, 2009 8:11 PM
Subject: Re: Transmission Noise ?

Sorry, the original thread got really long so I clipped off a lot of it.
Here's some quick answers. Scott's questions are in quotes: