* 2.73: A common ratio for fuel economy.
* 3.00: A balance between fuel economy and performance.
* 3.50: Offered better acceleration.
To know the gear ratio of a *specific* 1979 Mustang, you'll need to check one of the following:
* The vehicle's data plate (or "door jamb sticker"): This sticker often lists the axle ratio. It is usually located on the driver's side door jamb.
* The differential itself: The ratio is stamped on a tag on the differential housing (you'll need to get under the car to see it).
* The owner's manual (if available): The manual might list the specifications for that particular vehicle.
Without looking at the car itself or its documentation, it's impossible to determine the rear end gear ratio.
