I just did this service in my '00 GT Vert at 160K. It sounds like you are doing this yourself? I had mine done by a local Mustang shop that is reasonable and they do good work. If you are having it done check around, my quotes varied up to 3X.
The clutch "kits" sold generally come with the pilot bearing and throw out bearing. Inspect the flywheel and have it resurfaced if necessary. Mine didn't need it at 80K but it did need it this time. That is the rub, machine shops aren't what they used to be. A good shops "relationship" with a good machine shop will save you time, trouble and money.
Fluids, of course, it is time to replace those. I'd add the rear end fluid too. Your are under there and already messy anyway.
If you are having it done and trust your shop I'd suggest this. The T-45 is a bit weak and good parts are getting hard to come by. A specialist can evaluate your T-45 and let you know where you stand. Mine is and has been troublesome since about 4K after the warranty ran out (original owner here). If I continue on with my '00 I'll be replacing the transmission sooner rather than later.
Your mileage may vary,
Paul