Regarding the butt end of the Jenolan
, people seem to forget that there exists a clear photo of the stern of that vessel, too. Not only is the black area astern a cavernous shuttlebay going deep into the structure, it has a tiny observation deck right above the mouth! It was apparently created by ripping out the row of yellow lights (impulse engine?) from the original model and not filling the cavity with anything.
Now, if I only could locate that photo somewhere... The old IDIC Page had it, but that site is now gone.
The ST6 model was severely and permanently modified for the Jenolan
appearance - yet appears completely intact (but repainted) again in ST:GEN, and then
appears as the Sydney
in DS9. So apparently there were at least two separate models, of which only one was given the wings and nacelles. Or, more probably, the molds for making the ST6 remained and were used for making the Jenolan
's hull later on.