Do you Have a engine with a TBI manifold? 4.3 5.7 454? Don't have the computer and wiring harness? Or just want to convert to a carburetor. This is the part you need . Works with 2 barrel 350 and 500 CFM Holleys and early autolite carbs. Includes Mounting hardware nut's bolts washers ect. One holley 2bl base gasket It's hard to see in the picture but the bores are tapered to adapt the narrow 2bl spacing to the wider TBI pattern without hurting performance and airflow. Made from a duarable heat resistant composite automotive approved material gas and alcohol proof won't chip crack or stain. ( You would have to use an Axe to damage this material) Acts as an insulator to prevent the gas from boiling (Vapor lock) and keep the carb cooler for more power. Also adds tuned length for more TQ. Made right here in the USA on our in house CNC machines.