Back in 2012 I pulled my pump and sent it up to Cincinnti Diesel Injection for a full rebuild. Can't remember the cost but think it was around $500. I used a vibrating etching tool to add my name and telephone number on the side of the pump housing to make sure I received the same pump back. I did, and my truck cranks and runs great. They replaced all seals and flow-tested it on the bench. Follow the instructions in the TM and you shouldn't have a problem. A word of caution, however, there is a bolt that holds the pump to the housing which must be accessed through the oil-fill tube opening. You will not be able to see this bolt with the radiator in place. I used a mirror and, presto! there it was. When you go to remove this bolt care must be taken to prevent dropping it because if you do, you will have to remove the front of the engine to get it out. I crammed a rag into the oil passage under the bolt and then used a socket with a magnet to get it out. To reinstall it after the pump has been rebuilt, you have to make sure you index the pump correctly so the bolt goes back into the correct hole. Use the mirror. Make sure all injector lines are tight at both ends and bleed the fuel system without burning up your starter. Good luck!
