Ford's 4F27E transaxle is a four-speed (three gears plus overdrive) design that has planetary gears much like that found in an AOD-E application. One of the main problems with the factory unit is it was designed with very little line pressure, which slows down the shift feel and response. One of the first modifications PA does is to alter the valvebody to improve line pressure, which increases the firmness of the shift points. Note the arrow. This is the OEM vent tube that vents air trapped in the case.