Re: Was ANYTHING retained when the Enterprise was refit?
I always liked the fact that something that looks very much like the dilithium intermix chamber from TOS is still visible in the wall of Engineering in that footage shot for Phase II. Gave a nice feeling of "This is still the same ship underneath all the cosmetic additions". I'm not so sure if it survived to the TMP version of the sets, though.
AFAIK, that same engineering set with the dilithium chamber was built for Phase II, first used in TMP, and continued to be used in the second through sixth films plus the engine rooms of TNG and Voyager
"A hot dog at the ballpark is better than a steak at the Ritz." - Humphrey Bogart