if you are talkking about the O-ring that is inside the hose that goes to the high pressure side of the hose that is attached to the pump: i got the shop manual from helm for the 93 taurus(similar setup).. you cannot replace this O-ring as it is up in before the hose fitting is attached and is not servicable.. you get a new hose... the only O-ring i bought seperately was the one that went on to the electrical sensor that goes on the hose way down by the rack and pinion area... i got it at a local auto parts place, it does not have to be anything special... the guy asked me what it was for when he took out the metal storeage box of O-rings and we matched it up.... i know you did not want to hear this, neither did i when i had to change my hose due to a bad oring in the connection fitting of the hose... sorry.....