DEF Doser Urea Pump Assembly for Cummins Diesel Engine 5506956RX 4388105 5506956 Feature: High-quality material, good corrosion protection and best durability. Easy to install, direct fits. Compared with other similar products, our DEF Pump has higher performance. Please make sure it will fit your machine before purchasing it. Excluding installation instructions, it is recommended to use professional installation.