I want to replace the Low/Reverse Servo double lip seal. I just called the N. Seattle Ford dealership and was told that: "there are three pistons with different part numbers that vary with the number of grooves in them. Two are discontinued and the one that is available is an updated part no. and is $49. I think that comes with the new seal you mentioned. If you special order before 3pm, it should be in by tomorrow." Huh? Is that right? I hate to pay $49 and not KNOW I'm getting at least the seal. btw, I have not yet pulled out the piston to check for scoring (one of tonight's projects) but I think I only want the seal. Anywhere else I can obtain the seal? (does the updated seal come in a valve body rebuild kit?) or does anyone know the Ford part no. for just the double lip seal? I want to finish the easy replacement stuff before I rebuild the throttle body. I want to run the car with the new vacuum modulator valve, new low/reverse servo seal, and the correct amount of new fluid to see what, if any, improvements those create. If it still operates oddly, I will then rebuild the VB. I installed a transmission drain plug last night so future work will be a LOT less messy.