our cars have t-loks from the factory. you can upgrade to a 31 spline unit and 31 spline axles to help increase strength/reliability at the drag strip. i have a ford racing 31 spline diff and moser 31 spline axles. you can also buy a used t-lok differential from and f150 or explorer, both are 31 spline and will fit in the 8.8".
if you plan on upgrading to 31 spline axles you have to have a 31 spline diff. however, if you arent you dont need to do anything. you might want to consider replacing the clutches in your current diff though, makes a big difference.