The present invention contemplates a preferred position for mounting an antilock control system that uses a signal wheel speed sensor. The wheel speed sensor is mounted to sense speed of rotation of the main differential gear in a differential gear assembly and generates a wheel speed signal indicative of the average rate of rotation of at least two wheels of the vehicle. The sensing point is beyond the final reduction in gear ratios so as to eliminate any need to accommodate different axle ratios. The preferred mounting position also reduces velocity fluctuations caused by oscillations of the truck axle. A microprocessor controller is mounted in close proximity to the wheel speed sensor so as to minimize the length of sensor leads and, hence, the susceptibility of the antilock controller to electromagnetic interference. In the preferred embodiment, a single wheel speed sensor on one axle of a truck controls a solenoid valve that releases braking force from all the wheels of the vehicle in response to the wheel speed signal. Alternately, an antilock controller may be used on each axle and control only the brakes of that axle so as to provide axle-by-axle braking control.