Its been suggested by some that they might not absolutely be necessary, and maybe were only included on the factory injectors to keep them from falling off the fuel rail while on the assembly line under construction. But I'm convinced they DO serve some purpose, as seen here keeping the injector from being too deep or too shallow in the fuel rail bore.
I bought the same injectors you have. There was a note in the box:On some engines, including most GM applications, it may be necessary to install the retaining clips in the upper full circumference slot to ensure the injectors seat properly in the fuel rails and the intake manifold/heads.
Note that installing the clips on the lower
slot prevents the clips from rotating properly from the "unlocked" to the "locked" position. Use the upper slots.
And yes, that's the right part number.
I bought a set too; got it from Jegs.