ala_xfire, That is the same item my friend tried on his GT500. I thought it was installed on the positive side but maybe it was installed on the negative side. From what I remember about the switches in the 1990s and early 2000s on classic Mustangs was that they were used as a security device. The owner would completely unscrew the plastic **** and keep it in his or her pocket while at a car show, cruise night, or parking lot. It may work well on a Crossfire if there is enough room for it in the battery area.