4BT 3.9l Cummins Engines With VE Rotary Style Pump. High Performance Fuel Injector Pipeline. 1 Set Fuel Injector Line As The First Picture Shows. Note: 12mm Fittings On Each End. 12mm Thread Injectors Use A 17mm Wrench For Line Nut And 14mm Thread Injectors Use A 19mm Wrench For Line Nut.