The B&M T-Handle is a welcome addition to the 5-speed GT. The Bullit shift knob tends to get slippery under hard shifting and the T-Handle is a high quality shiny application that can provide a more secure feel for hard shifting.
The older packaging shows that the application will work up to a 2000 Mustang. The T-handle will work up to and including a 2005. The 2006 changed the threads and will not work with this shifter handle.
The 99-2005 have a metric thread on the shift lever and the B&M T-Handle comes with the adapter and jam nut required. Start by removing the stock shift knob or Bullit knob by unthreading. Remember "Lefty Loosy". You might need to apply a fair amount of force if you have never removed the knob before, but it will unscrew.
Choose the correct adapter that you require for the T-handle and apply a thin bead of thread lock to the last 3 or 4 threads on the insert. The thread lock is supplied.
Thread the insert into the B&M T-Handle. Install the appropriate jam nut onto the shifter lever and thread it about half way down the threaded portion of the lever. This is going to help thread the insert completely into the T-handle. Thread the T-handle onto the shifter lever and turn it until the insert is completely seated into the T-handle. Use a 5/8" wrench to loosen off the jam nut and remove the T-Handle. Clean any excess thread lock off of the T-Handle and remove the jam nut from the shifter lever.
The stock shifter knob is a fair bit longer than the T-Handle shifter. The leather boot maintains is position under the stock knob via a piece of rubber hose. You will have to cut a longer piece of hose to lift the boot up and hold it in position under the new T-Handle. Once you have a hose that is close to the correct diameter to fit on the shifter lever, use a little WD40 to help get it to install easier. Pull the leather boot up and over the hose and re-install the smaller stock hose on top of the adapter that you just made.
Re-install the jam nut onto the shifter lever with the flat side up to mate against the T-Handle. Install the T-Handle until it bottoms out on the shifter lever threads, then back it off until you have it in the desired position. Adjust the jam nut up against the base of the T-Handle and tighten sufficiently to hold the T-Handle in place. You will easily be able to remove the T-Handle by loosening the jam nut. It will take about 24 hours for the thread lock to cure.