The slave cylinder actuates the clutch arm by use of hydraulic pressure. Age and use wear this part out. The first sign is a vague clutch, followed by leaking and eventually total failure. This is a great thing to have around when your goes out, it is only a matter of time. If your clutch is not as crisp as it used to be, go ahead and replace it or keep one in the glove box just in case. This is a new, not rebuilt slave cylinder. We literally order these by the pallet load, and have excellent service from them. This slave replaces either 31470-60100. Fits 6/85-87 FJ60 Toyota Land Cruiser.