4 Runner Aftermarket Head Unit . If so, what did you replace it with? I may create/post a write-up if I have time, but I should be able to. Replacing Factory Stereo Head Unit - Needing USB and AUX ... (Nelle Andrews) What does matter is if you have a factory amplifier or not. We are dedicated to providing you with the best customer service around. The headunit doesn't output a signal like an aftermarket unit. Aftermarket Head Units often far, far surpass the features of the best? However, I want to maintain the OEM JBL amps and speakers as the system sounds good. Toyota 4Runner Instll Navigation DVD Entune JBL Steering ... Replacing Factory Stereo Head Unit - Needing USB and AUX ... 5th Gen OEM stereo head unit, P1850 - Toyota 4Runner Forum ... Toyota 4Runner install iPod Blue