Appears N705DN was unable to depart on LAX-SYD on 8 March LAX time and operated the service 24hrs late as DL9856. Return to LAX is presumably the same thing, 10th March service running 24hrs behind. No idea what happened in SYD to cause a further 24hr delay...
N701DN, on the other hand, is today's scheduled service
PS I believe the engine Kalitta delivered was for UA, not DL. Pretty sure I saw that somewhere, and also Kalitta arrived ex SFO.