These are the brake caliper tabs we use when building a Camburg rear end. These are designed for Wilwood's 3.5" lug spacing. They also work with radial mount calipers with the proper machined adapters. These are CNC laser cut from thick 3/8" steel and are setup to be through bolted with a 7/16" bolt. These can be MIG or TIG welded. Select your axle housing tube size and the brake rotor diameter. These tabs work with the following calipers. Wilwood 4 Piston Superlite Wilwood 6 Piston Superlite with adapter #250-6309 Wilwood Aero6 with adapter #250-14046 Wilwood Aero6-ST with adapter #250-14046.