Hi. I have a 92 4runner built in japan for the canadian market. I have no sound from any speakers. I'm going original because this truck is mint with only 25k miles. Found a replacement amp model #86280-35020. I checked fitment on a couple parts websites and it's supposed to fit mine but not a north American built truck. I took center dash apart and there is no amp behind ashtray. The radio is a Toyota model 56403. My question is, does this radio/cassette player need an amp and could it be a unit with independent rear amps? If so then the head unit is done.