Got the same rattle from an aftermarket Throw-Out-Bearing. I'm thinking you have the the Needle-nose type of T.O.B., instead of the one piece desighn the Ford Racing makes. Mine is a Zoom clutch T.O.B. and was replaced twice and still had that infernal rattling. Design flaw, or shall I say terrible design to make something at that high of R.P.M.s needle bearings , while the 2005's and newer have an Hydraulic T.O.B. that don't rattle.
Sometimes if you press a little on the clutch the squealing or a rattling will go away but, if I'm on streets for a while or in stop and go driving the T.O.B. tends to make noise no matter what is done to it.