Just save a few bucks and go to GM and get some stock rocker retaining nuts and they will be fine. Poly locks do work sometimes lol. They are a pain to set since you have to set the nut and use the locking allen to keep them there and if the top of the Rocker Stud is not flat then they may not hold a setting well or be hard to set. And if you are using a SB you can get a complete rocker arm assembly that will have the sloted rocker balls along with the nuts and long slot rocker arms for cams with over 480 gross lift so you will not split the rockers.