New Genuine Excel Water Pump Kit P/N 681806E includes O-Ring(as pictured). NOTE: There are a few options for water pumps with the DD15. Alternative and other replacement reference part numbers. Detroit Diesel EA4722000401, A4722001001, A4722000401. Detroit Diesel Series DD15 Water Pump. Excel p/n 681806E is #1 in the above diagram. If you have any doubt this is the correct pump, or please contact your local OEM dealership for correct part number to ensure correct pump. We’re an authorized dealer of PAI and Excel products, please let us know if there is any other parts you might need, thanks.