A first tooling component is positively secured to a second tooling component by one or more quick change locking couplers each including a cylinder secured to the first tooling component and having peripherally spaced holes supporting balls for radial movement. A stud is secured to the second tooling component and has an enlarged head portion projecting into the cylinder. A cup-shaped piston surrounds the cylinder and has a recess for receiving the balls in a released position, and a housing supports the piston for axial movement between the released position and a locked position forcing the balls to engage the stud. A compression spring moves the piston to the locked position, and air pressure moves the piston to the released position. A proximity sensor is supported by the housing and detects the piston in the locked position to provide an electrical signal to a remote visual and/or audio indicator.