If you plan to install or upgrade the original AOD instead of the electronically controlled AOD-E/4R70W, you will have to pay close attention to the Throttle Valve (TV) control linkage. The TV linkage or cable is used to tie the engine throttle to the throttle valve, located in the transmission valve body. The hydraulic circuits in the valve body use both Throttle Pressure (from the TV Valve) and Governor Pressure (proportional to vehicle speed) as the sole inputs to control all transmission functions. TV pressure is used to effect shift scheduling, but its most important purpose is to control transmission line pressure. Proper line pressure is critical to transmission durability and shift feel. It is important to adjust TV pressure properly and, for retrofit applications, TV linkage or cable fabrication must be completed correctly as part of the transmission installation. Failure to set up the TV system properly will produce one "deep fried" AOD. Owners of 1987 or later factory AOD vehicles should update the nylon TV cable bushing at the throttle body with the updated bronze part to protect their transmissions from the same fate. For more information about TV adjustment and linkage or cable fabrication, please read the section concerning