Actually those can be reused if necessary. They're soft copper so they DO NOT "work harden" over time and DO NOT need annealing with a torch as has been parroted all over IDI sites. It boggles my mind how some tried and true diesel shop procedure can be posted on the net and it immediately dies a quick death, but some goofball theory that's dead-wrong and dreamed up by someone who's total experience is tinkering with his pickup in the driveway (not referring to Chuckster) will spread throughout the IDI sites like wildfire.
Case in point, due to design and operation compared to a gas engine, anyone who has worked on diesels for a living would agree, the intake manifold of any diesel engine will be oily, dirty, gritty feeling, badly coked and carboned up. The other day a guy mentioned his was crudded up on another IDI site and about 20 clowns posted back and convinced the poor sucker to tear half the engine down to remove and clean the manifold.