there should be 2 seals for the hubs ( about 4 inches diameter) and 2 seals for the inner axle, (maybe 2 inches) they go inside the housing (inside the knuckle ball)
one thick one thin, then tighten it all down and see how much resistance it requires to turn the knuckle side to side most use a fish scale for this
they should be snug not sloppy or too tight to turn
there are actually 2 more gaskets about 4" in dia. these are for the spindle to knuckle