Ok so I've got an original a body 8 3/4 rear end to bolt up to my 68 Barracuda. So I'm changing axle shafts to the big bolt pattern from Dr. Diff when he gets some new ones in. Question do I need to upgrade the backing plates? If so to what size? Also do I need the flat iron bars that go inbetween the front and rear shoe of the rear brakes? Disc will be up front.