A power transmission has a parking pawl which is engageable with a toothed member on the transmission output shaft to prevent rotation of the output shaft when the parking pawl is set. The pawl is manipulated by a manual selector shaft and a detent plate. The detent plate is also drivingly connected with a transmission range selector valve through a pin which engages an annular groove in the selector valve. The pin is driven by a cam on the detent plate and is guided in a pair of longitudinal slots formed on the valve body which slidably houses the selector valve.