I have an electric retractable antenna on my Vanagon.
I looked through my paperwork, and I got the antenna from antennaworld
(http://www.antennaworld.com)

I got the SJ-3F antenna with the D-57 head. ($79 for the antenna, $7 for
the head.)

You can see pictures at:
http://www.antennaworld.com/eshop/Default.ASP?WCI=ItemDetails&WCE=D-57
http://www.antennaworld.com/eshop/Default.ASP?WCI=ItemDetails&WCE=SJ-3F

It seems that the trick is the angle found where the antenna attaches to
the body. It is difficult to find an antenna that will adjust to this
57-degree angle.

NOTE: In order to fit the electric antenna to the vanagon, I had to
enlarge the hole that is behind the driver's headlight, leading to the
compartment above. I believe I had to make approximately a 3" opening
for the motor of the antenna to fit through. Aside from that, the rest
was simply a bolt-in project.

Thanks go to Joel Walker who gave me the information initially.

Oh, and did i mention that retracting the antenna at hiway speeds
results in an increase of MPG by 2 mpg and a higher top speed by 5 mph.
:-)

Todd

'88 Westy