you cant put a monsoon in a car with a base stereo.
but you can add aux input port to the factory radio. How you can add an aux input/mp3 player without an adapter - LS1TECH i put this aux port in my regal, and another member did it to his GP. cost me 5 bucks, if you have solder iron, solder and shrink tubes already. got the wire at home depot, they sell it by the foot, 3 feet was 90 cents, the aux poet was $3 iirc. the part number listed still works. just hand the guy at the counter for the part #, you'll never find it on your own lol
you can tap the cd player, or the tape deck. or the radio. page 25 talks about it i think, up or down a page maybe. one guy did it.
my cd player was a thin ribbon, so i went and tapped the tape deck.