Do I need a code? Or a new #$%^&* car?

[angryred]

We have a 91 Mercury Tracer that is acting as a do-fer 2nd car. Several years ago the stock radio/cassette started acting funky. Playing a cassette causes a lot of crackly noise that varies with the sound-- the louder the sound, the more crackle. And the radio barely works-- there are no lights, and the radio just slowly cycles through the AM band, as though someone was turning the radio knob verrrrry slowly. Button presses have no effect; can't change the band, stop the station cycling, etc.

So I figure it's gotta be the radio. I go out to Pick-a-part and spend an hour in 100 degree heat wandering the wasteland of junked cars, and I end up pulling a radio out of a 94 Mercury Sable (IIRC). But when I plug THAT radio in, nothing happens at all; no lights, nothing. Power button does nothing.

So I head to Google and learn about these radio activation codes, of which I knew nothing until today (is that a CD player thing, or does it apply to these old cassette decks?). From what I can see, though, I *should* get something on the display that prompts me to enter a code, but I don't see anything.

My *other* issue is, the serial number on the new(er) radio is not in the same format as any of the ones I've seen in forums, etc. on Ford radios. The label says 'made in Mexico', the serial # (if I'm right) is MNHDO42263. The other number on the label, the model number, I think, is 96BP-19B132-AA. There is another number on the back, embossed on the black plastic wiring connector: F2DF-14A459-BA.

In all the code threads I've perused this evening, none of the serial numbers I've seen match the format of mine, so I don't even know who to ask for the code (if that's in fact what I need). I'm unsure at this point whether it's the radio in the Mercury that's gone bad, or if the wiring is somehow bad. The fuse for the radio circuit LOOKS fine, but...

...So right now I don't know if I need a code, need to suffer the heat again to exchange this radio, or if I need to shove the Tracer off a cliff and report it stolen.

Any insight would be greatly appreciated.