I upgraded my rear drums with SVT Rear disk brake kit. In total it cost $610 from Ford's SVT dealer on Dixie Rd - brand new - but you can probably find the same kit for cheaper.
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[MarcuS]
Rig:
SVT Rear Disk Brakes, Grounded throttle body.
[MarcuS]
Rig:
SVT Rear Disk Brakes, Grounded throttle body.