I am having an aftermarket radio put in my 89 300se. The fellow is a 30 year professional, but is stumped on the installation. I ordered a wiring harness from Crutchfield for the car and he is telling me that the plugs do not even come close to what is needed. He is wondering also if there is an amplifier in the car and if it will even work with the aftermarket installation? Can anyone help me with this that has changed out the old Becker and put in an aftermarket? Again, I have an 89 300 se. Any suggestions for easiest installation?