> The antenna on my 86 vanagon broke off; the local VW people said that I needed
> to replace the entire unit.  Well I have the antenna unit but I's stuck in
> terms of the installation.  It seems that the antenna has to be installed from
> the inside.  That is, push the antenna through the hole from the inside and
> then install the gasket and locking nut from the outside.  However, I can't see
> how to disassemble the dash plastic to install it from the inside.  If anyone
> could provides some assistance, I would be most grateful.  Thanks!

I just replaced the antenna on my '85.  BTW, Crutchfield Stereo, a 
mail order electronics place sells an exact Hirscham replacement 
antenna for about 12$.  After staring at the whole setup and trying 
to figure out the gromment/dash/hole in fire-wall setup I just forged 
ahead with this:
1.  Pull radio out of dash(poke small rods in the 4 holes in front of 
radio), disconnect the antenna and duct tape a flexible wire to the 
end of the antenna lead.
2.  Take the grill off and remove the headlight for better access.
3.  Unscrew the antenna nut and pull the antenna down into the 
headlight area, the grommet will pop out but don't worry.
4.  Pull the antenna lead out thru the radiator opening with the 
(securely)attached wire.  When the end that plugs into the radio 
comes thru, cut off the wire and fasten it to the radio plug end of 
your new antenna, be sure to thread the grommet on the lead-in.
5.  Pull the wire from inside the vehicle and pull the new lead-in 
thru the dash.  Mine didn't catch on anything and went nicely.
6.  Insert the antenna up thru the hole, attach necessary hardware 
and replace the grommet.  Voila!

Radio reception is *extremely* dependent upon a good ground where the 
antenna attaches to the body.  Clean this area well by using a stiff, 
hook shaped wire to scratch the inside perimeter of the mounting 
hole.