In the United States, the ball got rolling when Holbert Racing began making modifications to their own chassis and rebadging them with "962 HR-" serial numbers. The search was always on for a stiffer and safer 962 monocoque and Jim Busby contracted Jim Chapman to build a more robust version of the 962 monocoque. Fabcar would become the de facto factory tub supplier, supplying chassis with official Porsche serial numbers. Fabcar incorporated changes to the factory tub, replacing the simple sheet aluminum construction with a combination of sheet aluminum and aluminum honeycomb in addition to billet aluminum bulkheads. These changes substantially increased the tub's crashworthiness and stiffness. Dyson Racing purchased a Richard Lloyd Racing / GTi Engineering 962 monocoque for use in their Porsche 962 DR-1 chassis. A Fabcar tub was used in Dyson's Porsche 962 DR-2.