Good afternoon Gang...
Has anyone substituted the YS4z-6N664-BA with the XS4Z or Vice Versa? I work for Dorman Products and we have released the YS4Z into the aftermarket. Should be able to get it from major retailers if your OE dealer does not have it in stock or its backordered.
They are similar parts, except the XS4Z has insolation from the heat and the one end is shaped differently. Almost as if the 2000 Zetec has something to interefere with the XS4Z from working. See images:
