MACH I Member
Joined: Oct 2010
Location: Toronto / Houston
If the differential still has a sticker on the housing it should say what the factory gearing was. On mine it says 3.73.
2018 GT350 - Race red
2012 Mustang GT/CS - Race red - Electronics package - Security package - 3.73 - Steeda shift knob - Steeda shift bracket - ProCal II Tune - GT500 ABs - Shaftmasters DS - Boss 302S Wheels - Build date: February 14th, 2012
2011 Mustang V6 - Pony Package Premium Coupe - Black - Charcoal Leather - Roush Front Fascia - Matte Black Lemans and Hockey Stick Hood Stripes - 6% HP Charcoal Tint - 3.31