These are Speedway Engineering Drive Plates The standard for the Nextel Cup, Busch Grand National, ARCA, Craftsman Super Truck and Grand National West divisions. These are the drive plates used by all the race teams on their full floater Ford nine inch rear ends. These same proven drive plates have been used by professional racers for 25 years. They are a CNC machined, heat-treated 8620 steel forging that is dri-lube coated for long life. These are the best that money can buy. These would cost over $300 to buy new. Buy a set here and save big. These were purchased from a top NASCAR race team and were used for one race or less. They are in top shape and ready to install on your full floater Ford 9 inch rear end. These are the standard 24 spline 5 on 5 wheel pattern.