2001 Dodge Ram Front brake rotor removal

I have a brand new set of front rotors for my 2001 Dodge 2500 Ram, but have run into a road block. There is a large Trox headed bolt that holds the caliper bracket in place. I do not have that size of external Torx socket, and with the price of a complete set, I might as well have the dealer change the rotors for me. Do you know what size of Trox socket is required for the removal of this Torx fastener? Thanks!