they're widely available (Checker/Kragen/Northern carry GP Sorensen 8009220 for about $12 fit most ; save a few $$ at Autozone same part $9 - don't see your engine/year posted, but I'm guessing a '91 - these'll fit that, Napa, Autzone etc all should have some as well)
Go in with Year make and model -- should be an easy find.
You'll want em good and lubed for installation (I use KY, Sorry Chris...)
If you're following a FSM or other manual - the material that the seals are now made from has changed - most manufacturers don't color-code the rings for which end of the injector they fit on. Now it's one-size fits all (all qty=13 rings are black - 13th ring is for the fuel-pressure regulator)... and it does.
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Besure to count the rings that you get the 8009212 part number is a set for 4-injectors
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