Radio install
 

I have a 1988 and want to replace the original radio. I was told that I will need to run new speaker wires to either the front or rear speakers because the original setup used a common ground. Is this true? Can I just attach the new radio speaker wires to the original speaker wires?

Radio.
 

I hooked up an amplifier and it was wired with positive and negative to the speakers. Not a common ground.