On Some Transmissions, the Thrust Washer Union has a Ridge -A-
WARNING: This page is about a different car, the 2009 Volkswagen Rabbit, 2008 Volkswagen Rabbit, 2007 Volkswagen Rabbit, and 2006 Volkswagen Rabbit. However, it is still accessible from the selected car via links, so may be relevant.
Also, the differential housing has a groove -B- all the way around it.
-- Insert thrust washer union with transmission fluid.
-- Install the thrust washer union so that it fits into the groove -B- in the differential housing.