radio amp location F37F-19B165-AE

I have a new to me '94 Explorer 2-door 4wd with the factory am/fm/cassette player ... DNR on the door (I was told that means there
is a seperate amplifier someplace).
Everything powers on ... and sometimes I can hear very low (at full volume and no matter how I balance the speakers) music ... both on the am/fm band and with a casette.
I checked the fuses for the radio and the amp .. botha re fine (even ohm'd them out to make sure my eyes didn't fool me).
Not having an owners manual I ordered one and the radio guide is a seperate manual and wasn't aprt of my order. Bought an aftermarket (Haynes) guide and it was no help for this.
My questions are :
1) where is the amplifier hidden ? I traced the wires back from the empty hole I have in the dash now ... and see nothing helpful ... hanging upside down didn't give me a clue as to where it might be working back from the fuse panel (though I did find a brake control unit stuffed up there) and I also checked behind the glove box.
too cold to deal with a blind hunt, but I might go crazy listening to the tires hum (or worse yet .. I might start to sing ...) so a hint would be appreciated.
2) back of the radio there are spots for antenna, 8 large flat pin (power and ... , 8 pins I suspect are tot he (4) speakers all of which have wires going to them.
There is also a 6 pin spot and a 2 pin spot with nothing to them .
does anyone know what these are for ?
if any go to the amp I'm in trouble :^)
I googled the web and usenet without anything that led anywhere
                    thanks in advance
                        - Ed
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