^^ Well, the NX had a warp reactor
with 'plasma conduits' running to/from the nacelles, but I dont think we ever saw a vertical
warp core per se? Besides "Enterprise"
retconed so many things, it's the main reason many do not consider it 'canon'. But here's a thought FWIW, much ado was made in ST:TMP about "the new engines" implying that they were a radical redesign and departure from past systems? So much so, that on their first attemp at warp drive they were sucked into a wormhole! If the engines were simply a variation on past designes, then Scotty and his crew (not to mention Starfleet engineers in general) should have been familiar enough with the new system to avoid this? As a result, Spock had to stick his vulcan nose in Scotty's domain and help fix the problems, something that surely wouldn't have been necessary if Scotty had been as familiar with this design, as he would have been, if this was just a new twist on an old idea?