'72 Lebaron radio questions

[72.lebaron@xxxxxxxxxxxxxx]

The following radio is currently installed in my Lebaron:

http://www.pencilneck.com/imprad.jpg

It works on AM, but when switched to FM I can't get any signal. There's a 
slight buzzing from the speakers, but nothing more.

I've checked most of the after market radio installation supplies makers, 
and nobody makes an installation kit to facilitate the installation of a 
new stereo. Does anyone have any experience replacing this kind of radio 
with an after market system?

Also, when examining the radio I noticed some kind of pigtail hanging from 
the back of the radio. It appears to have maybe six or eight conductors. 
Any idea what this is for?

Thanks all!

DD