This system features the 6-piston, 6P caliper mounted to a 13", 2 piece slot, drill, zinc plated rotor. The 6P caliper has D.O.T compliant dust and weather seals and uses the popular D0731 pad type. Rotors are pre-assembled with NAS high grade stainless hardware. Baer’s unique backing plate not only acts as a caliper mount, but also houses a modern 1-piece park brake shoe assembly. Stainless braided hoses and hardware are also included. The 13” Pro+ fits most 17” or larger wheels. Fits 1971-76 GM Full Size Passenger Cars w/OE Large Pattern 10/12 Bolt Bearing on Axle (BOA) Housing Ends