this is taken right from the fj80 section of the marlin store..
Replacement master cylinder for older Pickup's and 4Runners with smaller bore (bore size is cast into right side of housing). Fits 1979-1995 Pickup/4Runner. Features 1" piston and residual valves for both front and rear. Works with both drum and disc brakes.
you should be perfectly fine without one sinse the master has one already built in..
