^What he said. Your head unit comes with its own metal mounting sleeve[cage]. Simply install it into the remaining gap of the radio opening, and push in the tabs to secure it into your dash.
2003 CD Silver SVT Sunroof and Machs
#1229 of 3985 Date of Birth April 21, 2003
Borla Cat-Back/SVTF tip, Steeda Short Throw,FRPP 9mm Plug Wires, Upgraded "Big 3", HIA Short Ram, Xcal2 tuned by FocusSport, SRF TB, EAP Wheels(thanks John), Audiophile sub(thanks John), Euro Grill(thanks Aaron)