What do I need to be GT???

You'll need a total of eight retainers, the page tells you everything you need and has the related part numbers as well...

When you are installing them make sure they are in the right place. Remember you are drilling into the body to mount them. Also put something in the holes to prevent rust.

I have installed them without the retainer rails many times and your even better off. Use what the manufactures have been using for the last 10 years. (3M Body Tape). I have installed GT kits, spoilers and hood scoops. The stock retainers are expensive and drilling holes into the body is another place for rust.