Keep in mind that most of the 11 foot miniature was repainted by the the Smithsonian before it was ever displayed and before those photos were taken.
All the links and information in this thread have shown this is entirely conjectural and most likely a misinterpretation: In the early 1980's the Enterprise
at the Smithsonian underwent clean-up and/or repaint to some unknown extent (i.e. after
it had been hanging there in its original condition since 1976)
I took pictures in 1980 and the underside of the forward nacelle caps still had the darker shape (repainted or washed off in the above bluish shot) and the lower starboard porthole was still there (it disappeared after
the early 1980's "work").
As far as we know; no documentation of the original condition (and paint job) has made it out into the public domain other than the uncrating photos. The top of the saucer is the ONLY part that has never been repainted since the filming of the show. In the above photos it shows no pencil lines on the bottom of the saucer but we know that they were there on the original before the initial restoration by the Smithsonian prior to it ever going on display.
There are these original black & white promotional stills with the harsh contrast / lighting that reveal details like the pencil lines on the underside of the saucer - which were still there
in these (bluish) shots (www.cloudster.com
) taken at the Smithsonian after
the "work". But - again - you have to look very close to be able to see these.