They are, sort of. While the rotor is separate from the hub, it actually mounts to the backside of the hub rather than the frontside like the GMT800/900 trucks do. They are held in place by having the wheel studs pressed through them into the hub itself. That particular rotor is also different from the later ones by havng a square hole through the center, rather than a round one. The square hole is so that it will clear the mounting flange for the hub assembly.
