Straight from Matts site...
"The '99+ brake lines that come with the caliper are direct bolt-ins for some of the fox3 '87-93 V8 cars at the hard lines. If the passenger side line does not work, you need a Weatherhead 7828 fitting to adapt it. On my '90 GT, I had to use 2 drivers side hoses and grind the passenger caliper a bit to accommodate this. But I got fittings from a convertible '90 GT from the yard, and they matched up perfectly on both lines! Go figure! Your mileage will most likely vary. The stock brake lines have a lip on them to keep them from rotating on the caliper. That would have to be ground off to use it with the PBR calipers. If you are going to upgrade, most SS lines use a round piece at the caliper end, so you will not have mounting issues on the caliper."