Pistons & Rings: 403 Olds (choose size)This is a good quality Silvolite standard piston and rings set for the 403 Olds, as found in 77 79 Firebirds & Trans Am. They are cast pistons. Stock sizes are Std. 020 & . 30. Sizes outside of this are normally ordered especially only> Keep in mind too.. this is much better purchased in a kit where all the other parts come together also.. but if you need pistons & rings we gott'm.