Thanks for the reply, but I have replaced several antenna masts and this particular box is not the motor or the mast section.
The box is mounted behind the antenna motor and the aluminum section is hollow (I think), about 18 inches long ... looks like an exterior dipole antenna for TV reception - it runs from the box to a horizontal body area near a seam just inside the fender - there is a clip-on metal bracket attached to it. Could it be the AM portion of the antenna system?
I never paid attention to it when replacing the mast and can only barely see it now without taking a bunch of the liner out - next job if I can't figure out more about it.
Am I off-base?
1991 350 SDL (200K and she ain't bent, yet)
former 2002 E320 4Matic Wagon - good car
former 1985 300 CD - great car
former 1981 300 TD - good car
former 1972 280 SEL - not so good car
a couple of those diesel Rabbits ...40-45 mpg