Abstract: A fluid pressure cylinder assembly is provided with a sensor for sensing the extension of a piston rod from a tubular cylinder. The tubular cylinder has a base block that seals the end of the tubular cylinder with an inner wall. The inner wall has a threaded bore for receiving the sensor housing, which has an elongated sensor rod passing into an axial bore in the piston rod. The piston rod carries a sensor element that moves relative to the elongated sensor rod. The inner wall is at an inner end of an access bore in the base block. The sensor is threaded into a bore in the inner wall using a socket that has a slot to permit a sensor lead to extend to the exterior of the socket and out of the access bore so the lead rotates with the socket in the access bore while the sensor is tightened in place. The base block is provided with a slot that extends to the exterior of the base block so that when installed the sensor lead can be extended out through the slot for connection to suitable controls.