The Ford Racing (FRPP) M-4204-MB Torsen Differential is the exact same unit found in the 2012-13 Mustang Boss 302 Upgrade Package as well as the Laguna Seca Package & the 2013 GT500. 

The Torsen Differential is a full time torque-sensing, torque biasing differential, meaning that it torque and differentiation are continuously managed between the two axles and biased instantaneously according to variable road conditions. There are no clutches or preload to worry about, in fact, Torsen's patented parallel gearing system is designed to perform for the life of the vehicle. 

The Bias Ratio indicates that the Torsen Differential multiplies what torque is available from the wheel that is starting to spin-up or lose traction and sends that available torque, multiplied by the Bias Ratio (2.7:1 in this case), to the slower turning wheel with the better traction.

This Boss 302 Torsen Differential will fit all 1986-2004 Mustang 8.8" axle housings so long as you plan on using 31 spline axles. It is a direct replacement for the factory Traction-Lok in 2005-2013 Mustang 8.8" housings.