You need to use a Hi Low Converter. They have a different name but I cant think of it right now. Basically it connects to your rear speaker and converts it to RCA connectors that you could connect to your amp. Then connect your amp to power (battery) and Ground to power it up. Last thing to do is connect yours speakers to the amp.
Also get a high Low converter with remote connection.
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You need to use a Hi Low Converter. They have a different name but I cant think of it right now. Basically it connects to your rear speaker and converts it to RCA connectors that you could connect to your amp. Then connect your amp to power (battery) and Ground to power it up. Last thing to do is connect yours speakers to the amp.
Also get a high Low converter with remote connection.