I googled that episode, now that you guys have refreshed my memory.
That GSC stuff was made up in the interim.
Back in the 70's, the reference was "hey that was the first ship with warp drive and vanished on her third voyage."
So I am sticking with "she was a really old Enterprise-type vessel."
Thats my story and I'm sticking to it. ...and *real* klingons dont have big bumps on their foreheads either!