Geo stereo wiring

Have purchased a stock Geo radio to re-install into my 1994 Geo Tracker from a wrecker: the only problem is, I've now realized that the radio I have purchased isn't necessarily a Tracker radio, it's probably from some other Geo product.  I have the male plug that goes into the radio, and the colours on it don't match up with what I know about Geo Tracker wiring schemes.  How can I find out what this radio was in originally (I have the model number somewhere), and then, how can I find out what colours are what?  I don't want to fry this thing, stock radios for Geos are hard to come by.

Thanks!

Take a look at the following 4 harnesses.  You may have gotten an older radio for your newer car, or vice versa.  You will need the 70- series harness to plug into the car, and the 71- series to plug into the radio.  Just buy the correct one of each, wire them together, and you've got the adapter you need.

http://www.metraonline.com/turbowire.aspx?make=55