I made a recording of my mystery noise.

Just to recap the facts:
83 1.9l manual
Did the pilot bearing a few weeks ago.  This doesn't seem like a mechanical
noise that could be related but this should probably be mentioned anyways.
For good measure, let me also state that we recently painted the poptop.

The noise never occurs when you rev the engine at an idle.

It also seems to not have a periodic nature, and doesn't seem to change
based on engine or wheel speed.
For this reason, I believe I can rule out CV joints, wheel bearings, etc.

(As a reference, almost all the times you hear the sound in the recording,
the van is accelerating.)

the recording is high quality, but I recommend headphones.  Speakers,
especially laptop speakers, won't be nearly as useful.

I would REALLY appreciate any suggestions.... I'm going to go crazy here
pretty soon!

Noise is at http://people.cs.uchicago.edu/~wes/vanpics/sample.mp3

Thanks!!!!!
Wes