You would've thought by 2003 cassette players in cars would be extinct...lol!! But to answer your question, yes it should be plug and play, take out the old one, plug in the new one.

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2002 X5 4.6is
1999 C5 Corvette
1992 Mitsubishi 3000GT VR-4
1994 Kawasaki ZX-9R
2005 Mazda 6 Wagon (Wife's)
1991 Mitsubishi 3000GT VR-4