This is a reverse pattern Pro Tree style transbrake valve body for the 1972up C4. Low/reverse band is applied in 1st gear for engine braking and for sprag protection. A must for high horsepower in heavy vehicles. Solenoid activation is not required for reverse gear which allows for more convenient street use. Uses external type solenoid which provides a faster release compared with internal type solenoid set ups as well as easier service. Valve body will fully function as a reverse pattern full manual valve body even if power to solenoid is lost or solenoid is not hooked up. For use with push in style modulators.