Do you have a Cummins dealer in your area? If so all they need is the engine serial number or the last eight of your vin# and they can get you what you need. If one is not close by maybe call one and see if they can ship parts to you. You can order a book from Cummins for these trucks that show every part they carry for the engine with all part numbers. It is the same book they use at the Cummins parts counter. I have one and it is a must have. Mine says Parts Catalog Chrysler 2000 Pickup.
The line you are needing if I understand correctly is the one that connects to the bottom of the T not the one from the VP44 or the back of the head? If so the Cummins part number should be 3942592, the seal grommet for all lines connected to the T is 3905351.
Scott