[rchippie]

what the pro's do to insure there diff's dont leak is as follows . They take some 150 or finner grit sand paper . Lay it on a flat surface. Then they take the diff cup & with the gear side or ( open side ) down . Then they use figure 8 motions to level out the surface of the diff cup & get rid of any high spots. Then some times they also use 2 seals .