If you haven't already bought the Clarion, you can get a free adapter fror your car from Crutchfield when you buy any unit from them. Go to:
http://www.crutchfield.com. 
I won't debate brand choices, but if you haven't bought the Clarion yet, there are others to choose from, and inexpensive ways to acquire systems.
However, if you already have your Clarion, or even if you buy one from some other source, Crutchfield sells the correct wiring adapter for your car for around $12. Call them at: 1-888-955-6000...
Downside: Depending upon the year of the car, these adapters may only allow for the older two-channel stereo systems, and will connect a unit to your built-in dash speaker fader. New stereo units have four-channel powered stereo, with the fader built into the radio/CD head unit.
If this is the case (and I doubt it with a car as new as a '94), to get full value of the new unit, you will need to bypass the MB fader. Otherwise, you simply give up two of the four channels (and half of the power) and connect through the fader. Be sure to ask Crutchfield if this is the case with your car. If so, and you aren't sure how to proceed, you can either ask how to on this forum, or have a professional installer do it for you.