Superior Ford E4OD E40D 4r100 Automatic Transmission Shift Correction Kit with boost Valve 1989-up. This valve body kit deals with these problems: Converter shudder Converter burn up Reverse problems Weak shifts Stack shifts Lube problems Front seal blow out New boost valve included to replace worn OE valve. One KE40D kit does regular, heavy duty and diesel applications. The Superior kit makes extensive pump modifications needed to avoid pump failure. Shift slippage is a real concern in this transmission. The Superior kit cleans up this problem very effectively. The KE4OD Shift Correction Package includes a metal replacement drain back valve to replace the O.E. plastic valve. The O.E. valve can melt, cutting off lube to the overdrive planets causing failure.