In a heavy commercial truck with a 'Full-Floating' rear axle, how is the vehicle weight supported and how is the drive torque transmitted?

1. The axle housing carries the vehicle weight; the axle shafts carry only drive torque and can be removed without jacking the wheel
2. The axle shafts carry both the vehicle weight and the drive torque
3. The axle shafts carry the vehicle weight, while a central torque tube carries the drive torque
4. The wheels are bolted directly to the axle shafts, which are supported by a single bearing at the inner differential end