Rob,
Big engines can be gagged if inop before departure ( But not In Flight
)
On RB 211 the fan is gagged by legs going through the fan blades and locking them to the fixed stator behind. This stops the fan turning, then a blank ( two semi circles) is fitted over the core engine to stop that rotating.
Podded engine are normally gagged so no fuel/oil requirement.
The original Big fans ( JT9, CF6 and RB211) were a pain to move as the the engine was basically one big lump with this big 12-15 ft diamter fan on the front. This needed a freighter aircraft to ship it hence the need for 4th ( L1011) and 5th ( B747) pods.
Later engines like the Trent ( and I'm sure the other lessor known makes) can be removed leaving the fan on wing and the rest just fits in a suitcase
and goes in the cargo bay