plugs?
this might have been posted up here before but what type of plugs do the speakers use in the unit. Like are their just separate wires or are they like audio plugs for a tv?
Can you be more specific? Are you asking about the end that plugs into the radio, or the end that connects to the speakers? They both have connectors on them. The radio side has one or two big connectors with all kinds of wires ran into it. The speaker side has a male and female part to them.
the side that plugs into the radio. do all system have the same type of plug?
To tell you the honest to God truth, I'm not exactly sure. I do know that the HU's with the subwoofer has an extra connection to them. (for the sub) And if you bought the OEM sub, you will need the wire harness for the sub, plus the HU to make it connect up. As for the Power and such, I would say there is a good possibility that they will match. I do know that if the unit didn't come out of the same vehicle (ST-ST, F150-F150, etc) you may run into problems. I changed my dad's F150's cassette deck to a cd/cassette deck (exactly like mine in the ST) and we had to get an aftermarket adapter to get it to hook up. Best way is just to check what you are looking into changing it to, to what you have back there.
Check a site like Crutchfield, Metra, or Scosche. Chances are, the ST shares radio harness with many other Ford vehicles. It gets a little more tricky of you have Audiophile or "Premium Sound" (factory amps). Some aftermarket radios do not play well with factory amps (at least it didn't in my 2Gen Explorer).