The unsurpassed braking capacity of the Forged Narrow Superlite 6R six-piston caliper serves as the base of this 12.19” big rotor kit for the popular 1963 thru 1987 Chevrolet & GM C10 / C15 Trucks with Wilwood's new 1 Piece Iron Drop Pro Spindles. SL6 kits are engineered application specific for simplified installation and full compatibility with OE master cylinder output and ABS functions where used. Big brake kits provide increased brake capacity and complimentary style with wheel, tire, and suspension upgrades. Optional caliper finishes and rotor designs simplify personalizing the style and braking requirements of any application. This kit contains hubs with 5 x 4.75” and 5 x 5.00” bolt circle.