FAD vs 1-piece
RCV axle kits for the JL are offered in two versions.
RCV FAD JL axle kits retain 100% functionality of the OEM Front Axle Disconnect design. The kit includes a 2-piece inner passenger-side shaft, with an upgraded RCV coupler and bronze bushing. The FAD module will control the disengagement exactly as OEM.
RCV 1-piece JL axle kits replace the OEM 2-piece axles and FAD coupler with a single shaft. The inner shaft is designed to fit the FAD axle seals, and provide clearance to re-install the FAD module. The FAD will function, but the instead of shifting the coupler in the axle, the fork will just move across the inner axle. This does not cause any functionality issues or dash lights.