From Snap-On:
>>YA180A On-Car Brake Lathe Overview:
The YA180A On-Car Brake Lathe mounts in place of the brake caliper and enables the technician to resurface a front wheel drive car's brake discs while they are still on the car. Special mount fixture reduces set-up time by providing a quick reference for spacer requirements and correct link spacing as well as cutting tool centerline. The unit mounts in place of the caliper and the vehicle turns the rotor during machining. "Dead-on" accuracy in only 8 to 12 minutes<<

I guess you could use it on the rear wheels of RWD cars??