Engine: Big block Detroit Diesel (up to 515 hp) or Big block Cummins (up to 500 hp). Transmission: Allison EVS 4000 Series. Alternator: Up to single 400 amp. GVW Ratings: Front: up to 24k Rear: up to 58k. Frame Rail Size/RBM: 13 3/8" (33.98 cm). Front Axle Suspension: TAK-4® Independent Front Suspension, 18K to 24K. Cramp angle: 45-degree cramp angle. Rear axle suspension: leaf or air, single or tandem. Mirrors: Door-mounted, corner-mount mirrors optional. Steering wheel: 4-spoke.