The Dorman Genuine Coolant Reservoir 603-203 is a commercial truck part designed for maintaining the proper level of coolant in the vehicle's engine. Manufactured by Dorman, this coolant reservoir is a reliable and quality product that is essential for the cooling system of commercial trucks. With the manufacturer part number 603-203, this genuine coolant reservoir is a trusted and durable replacement part for commercial truck owners looking to ensure their vehicle's engine stays at the optimal temperature during operation.