Upgrade your classic Mopar braking system with this 4-Bolt to 2-Bolt Master Cylinder Adapter Plate. This adapter is required when converting from an early-style 4-bolt master cylinder to a later-style 2-bolt master cylinder. The adapter allows you to take advantage of the slimmer late-model master cylinder design, helping save valuable space in the engine bay while providing the opportunity for improved braking performance when used as part of a properly matched brake system.