When I had Injector RX fix my pulsation dampeners on my fuel rail of course they put all new o-rings on the injectors, debate by some is that you can reuse o-rings, DO NOT. I learned after I had my fuel rail all fixed up that I would just REUSE the o-ring on the fuel regulator thing or when ever that is on the forward part of the pass fuel rail. I just reused the o-ring on that, popped it back and the car and BAM gas coming out of it. O-ring was toast once I pulled it out at 99k miles. So I was like CRAP, where am I going to find this, one frickin little ring keeping me from driving her again. Again i went to jag for the ring, not sold as a serviceable part I am told. So I took the whole little unit to a Ford dealer (knowing some parts on these are Ford) and they pulled the part number off of the unit and brought out me the o-ring that fit it.
So if you are jammed up like I was try a Ford parts dept for part# w705818*s300 description of: sp seal. Don't recall if it takes two or not as I bought 2.