These are just a few that I have taken off original unmolested 1970 Chevelles. They are from left to right, S B, S B C, W E F and the triangular design 5/16 x 18 x 1 1/2". Both AMK and Paragon have a very similar bolt with "S R C on the head instead of S B C. I doubt anyone would notice and if they did, they should be shot.
