Audio Systems: radio swap, factory radio, cadillac deville

Question
i have a 1991 cadillac deville,and i want to swap the  factory radio, it has in it now, with a with another factory radio out of a 1989 or 1990 cadillac. the radios are exactly the same, except for the connecting harness ports on the radios are different. is there any way that a connecting harness or any thing to connect the 89-90 radio to my 1991 harness. the radios are not bose, they symphony sound.    ........... thanks

Answer
Sorry it took me so long to get to your question, I was on vacation and forgot to click the away message.
you'd pretty much have to cut the harness out of the car the radio came from.  I'd use a meter on it first before you do this and write down what each wire is for.  if you need help with that, I can help you,  just tell me when you have a meter.  Make sure that when you cut it you leave enough lenght to splice onto the harness, and if you plan on puting a radio in the car you're taking it from, leave enough length there as well if you can.  
Then you can get a wire harness for the car the radio is going into.  the new harness will plug onto the existing plug and keep you from having to cut it.
then its just a matter of matching up the wires and you're done.
Good luck and let me know if I can assist further.