Since you have the late 04, the dummy plugs and standpipes o the oil rails are common leak points, so you definitely need to check them with an air test. IMO the best way to do the air test is with the IPR test fitting and put air through it. Also, the injectors may be leaking, so having the valve covers off so you can hear leaks (if any) at each injector is almost a requirement.
Best to do the air test with hot oil. You need to give the air time to push the oil out of the system, which happens faster with hot oil.
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