Exhaust Manifold Gasket: Pontiac "D Port" FIBRE PrThis is a fibre gasket not metal. Yes these are considerably better then normal exhaust gaskets for older cars and YES they are considerably more expensive. You pay for what you get in a nutshell Most Pontiac Heads used this gasket.. the "D port" series.. 95% did.. & these are for use on older manifolds or hedders, Ultra Seal, Steel Core Laminate, Open Center Port where a metal original style gasket will not take up the micro gaps that may have