I think you do. Are you willing to take a look? Remove the center panel around the radio and then the radio itself. In the hole where the radio used to be, follow the wires from the back of radio, if they go to a silver box with fins on it, thats your factory external amp. On the other side of that amp is two plugs, they are the standard toyota plugs and should plug into the back of any toyota radio with an internal amp.
Hope this helps...
Matt