Lit

what are they? what do they do? also whats a T/A cover?

code3GT

The splines are on the end of the axles. The stock spline count is 28 on 99-04 GT's and it's basically 28 "ridges" for lack of a better word, on the axle end. These splines fit into the carrire or posi unit. A TA girdle replaces the rear end cover and while bolting in the same places as the stock rear end cover, there is also a brace that bolts to the main, inside the rear end to prevent twist and flex.