The Actuator Feed Limit Valvetrain Assembly is responsible for regulating/limiting line pressure to a calibrated value of 105 to 125 psi., known as Actuator Feed Pressure. This Actuator Feed Pressure is then fed to the Electronic Pressure Control Solenoid or EPC Solenoid, where it is regulated to between 0 and 95 psi., which is known as Torque Signal Pressure. This Torque Signal Pressure is then fed to the Boost Valve Assembly which is used to regulate line pressure in relation to engine torque. In the forward operating ranges, Torque Signal Pressure acts on the smaller diameter land of the Boost Valve Assembly, and in reverse range it acts on both the small and large diameter lands of the Boost Valve Assembly. Normal or excessive wear anywhere in the Actuator Feed Limit Valvetrain Assembly or crossleaks between circuits along the described fluid path will result in increased Actuator Feed Limit or Torque Signal oil pressure values. This causes the boost valve assembly to create excessive line pressure when operating in reverse range, resulting in the failure of the cast aluminum reverse servo piston. This billet aluminum servo piston is fortified in all critical areas and will not fail like the OEM design. Do not overlook this component during an overhaul. The longer the transmission is on the road, the more the wear that will be realized at the mentioned areas that result in reverse servo piston failure. This component will fit all 1997 and up 4L80E transmissions. LOOK CAREFULLY AT OTHER DESIGNS. IF THE INSIDE DIAMETER OF THE REAR SERVO COVER IS NOT MACHINED OR SLOTTED FOR SECOND ACCUMULATOR OIL FLOW TO THE TOP SIDE OF THE 1-2 ACCUMULATOR PISTON, IT IS NOT A PROPERLY ENGINEERED COMPONENT.