Other than the starship chart in "Court Martial," there was no other use of NCC for an explicitly non-Enterprise type starship in TOS. As Christopher points out, though, by TAS they were comfortable showing the freighter Huron with it. So, it's possible that the intent changed.
Except we don't know what the intent was during TOS, since they didn't have the budget to depict any Starfleet ships of different classes, and thus it never came up.
All the ships in the "Court-Martial" repair chart have been subsequently interpreted as Connies (first by Greg Jein, then by the ST Encyclopedia
which copied Jein's list), but I doubt that was the original intent. Given that there were only supposed to be a dozen Connies in the fleet, it's vanishingly unlikely that ten of them were under repair at the same starbase at the same time. Plus, we know that Jefferies intended "1701" to mean the first vessel of the 17th ship class, so numbers like "NCC-1831" and "NCC-1672" on the chart would've represented different classes by Jefferies's thinking. So I think the intent probably was that those various NCC numbers applied to ships of various different classes. Thus, there would have been no change in intent in TAS and after.