no you don't need to rewire it. I have a basic JVC deck in mine running through the fader. Only front channel is used off the deck running both sets of speakers via the fader.

I am also wanting to redo my speakers.

Search for a deck called "USA-4DIN" by customautosound. I am really considering one of these. They look really cool and you can connect with a usb cable.

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1982 300sd, new project car to restore

It doesn't matter if you know what you're doing, as long as you look like you know what you're doing.