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[RAAMaudio]

I have not removed mine yet to check it out but can say it should be rather easy to do so. The harness is most likely a general Toyota one but yours may have the factory amp, not listed in the full service manual and not sure about the parts listings in the Micro Fiche I have, no reader yet for it.
Generally they are an easy swap, just pull it out and take it to a good audio dealer to see what they have for adaptors. I usually just hard wire them myself but have been doing this for many years.