What turtle said...
The factory 1968 disc setup is nearly identical to the 73, but you do need to use 70-73 Mustang outer tie rod ends as they have the correct size taper. Calipers, pads and the caliper hardware kit is the same 68-73, but you'll use '68 disc style flex hoses, brake lines etc. The bearings are larger for the 70-up spindles, use the application for the 70~73 - Timken SET12 & SET13.