Was ANYTHING left over from the original design?
Uhura's communications earpiece!
When they started filming TMP on the bridge, Day #1 of principal photography, Nichelle Nichols asked Robert Wise, "Where's Uhura's earpiece?"
No one had thought to make one. The props guy ran down to the Paramount props storage and located a box with two TOS earpiece props in it that had sat there since the 60s, and brought it straight to her.
For ST II, the earpiece was replaced with a newly-designed prop.