Its an alternator that makes your call pull 3G's on a drag run.
Its a newer generation alternator that puts out more power than the 2g alternators that came on Fox body stangs. The fan is on the inside of the 3G housing, where on a 2G the fan is on the outside. 3g's put out more power normally around 130, where a 2g puts out maybe 75-80.
__________________

Derp!