ac delco rapid fire spark plugs sold by mostly advance and autozone.
This are a fince tipped platinum plug that was assigned as a stock replacement plug for many gm vehicles, even those that never had platnum plugs
Never under stood that.
My experience with them was very poor and very negative
I recommend using the r43ts cr43ts if running a stock or just warmed over stock. If you running bigger power I recommend the r42ts ro the CR42TS.
The CR plugs are readily available and the ones I recommed.