Coat the lip of the new front cover oil seal with clean transmission fluid and press the seal into the front cover using the proper tool. Apply sealant to the transmission case mating surface, then slide the gear assembly onto the adapter plate by tapping it with a rubber mallet. Next, apply sealant to the adapter plate mating surface and install the rear extension, torquing the bolts to specification. Fit and install the main bearing snapring, then measure the distance between the bearing surface and the transmission case to determine dimension "A," which will help select the proper thickness counter shaft front bearing shim. Install the front cover with a new gasket, followed by the return spring plugs, check ball, return springs, and select check plunger in their proper locations. Install the control housing with a new gasket, remove the transmission from the holding fixture, and install it in the vehicle, ensuring to fill the transmission to the proper level, which is 4½ pints for the FS5W71B type and 4¼ pints for the FS5W71C type.