I gave my Blu-rays a spin last night to check out some of the Excelsior
In ST III they really avoided showing any
vertical intermix element in the Scotty-Styles "Good night and up your shaft" scene.
While this could have been deliberate to avoid confusion with the engine room of the Enterprise
, the back wall looks so vastly different from what we had seen in TMP and ST II (sufficient distinction, IMHO) that just showing any vertical intermix shaft element might have been something they tried to avoid.
Did the whole set still exist by the time of ST III or had they just used some leftover elements for Excelsior
's engine room?