gear change

Putting 3.55 gears in my auto 13 GT. Wonder about the following: 1). Ford Performance Traction-LOK Rebuild Kit with Carbon Discs, is this necessary to Change? 2). Is the Ford Performance Differential Cover; worth the $$?

Drivetrain issue! Ok so i have an 03 cobra with a solid axle swap (bought the car like this) and the stock t-56 6 speed i noticed when banging gears/ racing there would be like a looooong like 1 sec gap between shifts like its delayed to grab the next gear even though i had the clutch out and...