For both performance and stock applications these plates replaces the stock steel plates (if equiped) and spreads the bolt load in the corners of the pan to eliminate leaking. These plates are a perfect match to the BOP Engineering One-Piece Oil Pan Gasket OPG49 and with the OPB138 Bolt Kit. At BOP Engineering, we have specialized in Buick, Olds, & Pontiac for over 25 years and have a reputation second to none in service and quality. Buy with confidence.