Allison C-2 Clutch Hub Product #: 109300 Allison C-2 Clutch Hub TCS has addressed the early failure of the C-2 clutch hub in high torque/horsepower applications with this new billet steel clutch hub. Made from 4140 HTSR billet steel. Zinc Chromate finish. Spline is lengthened .125" for more contact, plus a spline boss diameter increase of .100" for added strength. No weight penalty for strength. The TCS hub is only 2.8oz. heavier than the O.E.M. part. Comes with a modified thrust washer. Machining modification to P1 Sun Gear Required.