If you're using your factory radio or 8 track, you'll need 8 ohm
speakers. Most new aftermarket speakers are 4 ohm & unless you wire
them in series, you'll risk damaging your radio. Wiring in series
isn't the best option, either, since you'll end up with mono instead
of stereo. Here's a link to Turnswitch, who makes hi perf 8 ohm
speakers & I'm considering their 4x10 dual speaker for my center dash
speaker. http://turnswitch.com/speakers.htm
I had 5 of their speakers in my Challenger w/ am 8 track &
it sounded awesome. Scroll down when you open the link & you'll see the mopar 4x10.