When we got to CAGE Off-Road in St. Helens, Oregon, the folks there had already bolted a complete kit onto the fullsize Ford (an F-150, not a Bronco in this case) and had removed it for inspection. We arrived just in time to see the CAGE head unit being examined. CAGE head units (instead of the factory radius arms) bolt to the factory C-caps around the rubber C-bushings that Ford used. If you're a Bronco owner then you know how many times you've replaced these bushings. New urethane C-bushings are provided with the correct degree of caster for the lift you're trying to get, either 3 1/2 or 5 1/2 inches (using the complete kit with progressive-rate coils).