Actually the holes are not tapered, they are more of a hour glass shape. As the ball studs are pressed in the bottoms swell to hold them in place. Think of a rivet and how they hold. Its tuff getting them out, but you want that on steering parts don't you?
A true tapered tie-rod or ball joint uses two different taper angles to hold them together. One is very slightly different then the other, thats why a taper joint will hold even when the lock nut is backed off.
Joe
