I know. LOL. I stole them from you this morning. And, when putting them into my Jeep Stuff folder, found out I already had them!!!

 

X 3-1/2 Guess I'll stick that in the link in my sig...

 

So for my 88 Renix 4.0L I would need one of each? (One 5/16, and one 3/8)
One is for the fuel send, and one is for the return line, correct? (which is which???)
Then, in addition to the 12 fuel injector o-rings, I would need a 13th o-ring of same size for the fuel pressure regulator?
Is there anything else in the fuel delivery system that should be replaced? I like to do things once so I won't ever have to go into the fuel rail again, should I look at replacing the fuel lines? How about the FPR? Does that go bad ever?

 

I'm not the solid answer. The fuel line deals take two O rings with a spacer between them. You can't get that spacer, so save yours or go to the JY if you lost any. As far as the FPR, I guess it's rare that the diaphragm ruptures and raw gas gets sucked right into the manifold. Especially with Renix, (87-90), I question that the replacement part('s) are any better than the ones you already have. With rare exceptions, just clean it, make sure the wires are good and you are all set.

IIRC Cruiser and "us" never clarified the 5/16 vs 3/8, only that the spacers need to be reused. Mine might be 5/16.

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How about the middle line, > Napa 730-5017 5/16 Viton individual orings $1.35 each
Two for each of the three fuel line connects, with the spacer you saved between them.

Then Viton for the injectors. Make darn sure as you press the injector in, you don't pinch the O ring! Some tyranny fluid, oil, heck bee's wax! Viton won't care, just lube it.

 

This^^. Grab 2 each of o-rings.