Traditionally, shifting was controlled through the use of a valve body. The valve body is a hydraulic controller that takes pressurized hydraulic fluid from a pump and controls fluid valves, servos, and check balls. Inside this component lies a fluid labyrinth that controls the shifting functions of the tranny. Later model transmissions rely on electronic control from an engine control module, instead of the fluid management, to send commands to a control valve assembly on the transmission. In this case, electric solenoids, instead of spring-loaded valves, actuate the shifting action. On non-electronic trannies, swapping to a manual valve body eliminates the auto shifting and requires you manually shift into each gear. The benefits include quicker shift transitions and the ability to run higher internal fluid pressure for reduced clutch slippage.