Earlier I had posted about a water leak that was coming from my antenna.  
That antenna was the cheap Bug antenna.  I have recently come across a VW
antenna for the Vanagon.  I put it in and that night it rained.  When I put
it in, I did not have my sealant that I planned to use (it was in another
city).  I went out the next morning and wondered it leaked.  Well, it did not.

I had replaced the ordinal Vanagon antenna when I bought my VANAGON because
the plastic angle piece that the antenna goes through, had cracked and was
causing a leak.

I had been having water leaking and I thought by fixing the antenna the leak
would stop.  It continued. Then I sealed the windshield, and still a leak.  
Then after a rain, I felt around under the dash and finally traced the leak
to the antenna.  

I removed it and applied sealant to the gasket under the antenna.  The
leaking stopped.  But soon the leaking started again.  I tried a different
sealant.  The leak then stopped during rain.

I has snowed a few times and the leak started during the time I had the bra
on and the snow and ice built up around the antenna base.  I had also bumped
the antenna causing a leak.  Tightening the nut stopped the constant drip.

Some differences between the antennas:

Mounting: both mount the same but with two major differences
1) The bug antenna has a tab only on one side under the metal.
The Vanagon one has mounting tabs on both sides under the metal.

The tab missing on the other side did not allow the base to be tight and
created the water leak.  Adding sealant worked until the antenna was bumped,
then a leak and more tightening...

The other difference is the extension on the Vangon antenna that is missing
from the Bug.  The extension fits into a lower part of the sheetmetal to give
the antenna better support from the wind.  

YOU must BLOCK the hole off or you will have a leak into the inside of the
van.

This means that the Vanagon antennas base has better supported in the wind.  
Less damage to the hole in the body where the antenna passes over time. And
more leak resistant


2) The diameter of the Ariel:


The Bug antenna is larger than the Vanagon antenna (at least the current
replacement)

More wind noise and resistance (after checking, I have gained one tenth of
one percent to the hundredth power of gas improvement)


3) The other difference is that the Bug antenna would stick up about 6 to 8
inches above the body in the fully retracted position.
The Vanagon antenna will go flush with the body.


Opinion:

If you need to replace the antenna get an automatic retracting rather than
the VW one, cost will be the same or less with the motorized one.

Avoid the cheap Bug unit and IF you must use it, apply sealant to the gasket
base, be careful to not hit it and block the hole in the sheet metal above
the headlight to avoid water from getting into the Vanagon as you drive in
the rain.


This is my story and I am sticking to it...
Robert