OK....I went to Auto Zone and purchased an O2 sensor for a 1990 Ford Mustang 302. I understand that the clip on the end has to come off in order to splice the new sensor onto the old leads. I'm just not shure what wires should match up. Does anybody have a tip on this? BTW this is going into a 1987 420SEL. Are there any compatability issues that I should know about? Thanks!