lol the fuck?
calipers and drums are different types of brakes. if you mean the handbrake, aus del r31s use a ultra homo intergrated twisting style handbrake. theres a lever on the back of the piston, when the cable pulls on it it pushes the piston in. theyre prone to seizing up especially with a hydo handbrake so avoid using them. vb-vs coonadore calipers are the same but without the handbrake mechanism so if your making a diff or something and you dont need a cable handbrake, check them out.
HR31s have the internal drum style handbrake though but they are semi trailing arm rear